This small brittle star is obtained by dredging at the head of Lagoon Pond, Martha's Vineyard, and at Provincetown, Mass., although it is not available in large numbers. It is found with Ophioderma brevispina. Amphipholis is hermaphroditic and viviparous, and is probably self-fertile (Fewkes, 1887).

In New England, mature eggs and young in various stages of development have been obtained during the middle of the summer and on until the end of September (Fewkes, 1887; Coe, 1912). Animals obtained in the British Isles and New Zealand indicate that there may be a prolonged breeding period, which possibly extends throughout the year. At Plymouth, England, they are reported to breed from May to September (Garstang, 1931), but specimens collected in February, during an exceptionally cold winter, carried embryos of various stages (Fell, 1946).

PROCURING AND HANDLING MATERIAL

A. Care of Adults: The animals may be kept in aquaria or petri dishes, supplied with fresh sea water which should be inoculated at intervals with diatoms, such as Skeletonema (Fell, 1946).

B. Procuring Gametes: The ova are produced singly, and are liberated directly into the bursae where they are fertilized. Attempts at artificial fertilization have been unsuccessful.

C. Preparation of Cultures: Embryos in various stages of development can be removed from the bursae or brood-pouches of a mature adult, using the method described by Fell (1946): The animal is anaesthetized using a 2-1/2-5% solution of menthol in sterile sea water. With fine tenotomy scalpel and forceps, the disc, with bursae attached, is separated from the arms and mouth skeleton and turned oral side upward. The free-swimming embryos are disentangled from the membranous walls by directing a stream of water from a hypodermic syringe into the bursae. The younger, attached embryos are excised with fine scissors.

The embryos should be pipetted through several washings of sterilized sea water, and then isolated in five-cm. watch glasses containing two to three ml. of "Erdschreiber" medium (Gross, 1937), which provides certain vital nutrient substances. The watch glass is set in a larger petri dish, together with a sterile swab of wet cotton wool. The whole set-up is placed on a water table in order to keep the temperature moderately constant. The medium should be renewed every fourth day. The embryos are very susceptible to bacterial toxins, but by using this method they may be kept for several weeks and will differentiate normally.

D. Methods of Observation: Polarized light is recommended for studying the developing skeleton in these rather opaque embryos.

A. The Unfertilized Ovum: The mature ovum is orange-red in color, and measures approximately 100 microns in diameter (Fell, 1946). It is enclosed within a thin membrane, which is closely associated with the underlying protoplasm. The egg is opaque, due to the presence of yolk, and is shed at the germinal vesicle stage.

B. Fertilization and Cleavage: Little is known about fertilization and cleavage in this species. Two polar bodies are extruded and are retained within the fertilization membrane. The early cleavages are presumably total and regular. A modified form of invagination produces a gastrula with a reduced blastopore and no true archenteron. The pigmentation becomes restricted to the cells giving rise to endoderm (Fell, 1946).

C. Developmental Rate: No details are available.

D. Later Stages of Development and Metamorphosis: The young embryo becomes attached soon after hatching to the wall of the bursa. It is a vestigial, bilaterally symmetrical and oval-shaped pluteus, which corresponds approximately to the central portion of a normal pelagic ophiopluteus. A reduced calcareous skeleton, oesophagus, stomach and intestine are present, but anus and mouth openings are lacking. The embryos are very opaque and contain a cluster of orange pigment near the "anal" pole. The primitive gut degenerates as the growing embryos are converted to a more transparent, pentagonal form. At this stage, the attachments atrophy, and the embryos break off and lie free in the cavities of the bursae. Here they complete their metamorphosis. The young animals crawl out of the bursae when they have attained the adult form. Figures of these stages are to be found in papers by Fewkes (1887), MacBride (1893), Metschnikoff (1869), and Fell (1946).

COE, W. R., 1912. Echinoderms of Connecticut. Conn. State Geol. and Nat. Hist. Surv., 19: 1-147.

FELL, H. BARRACLOUGH 1946. The embryology of the viviparous ophiuroid Amphipholis squamata Delle Chiaje. Trans. Proc. N. Z. Inst., 75: 419-464

FEWKES, J. W., 1887. On the development of the calcareous plates of Amphiura. Bull. Mus. Comp. Zool., Harvard, 13: 107-150.

GARSTANG, W., 1931. In: Plymouth Marine Fauna. Second edition, Mar. Biol. Assoc., U. K., p. 295.

GROSS, F., 1937. Notes on the culture of some marine plankton organisms. J. Mar. Biol. Assoc., 21: 753-768.

LUDWIG, H., 1881. Zur Entwicklungsgeschichte der Ophiurenskelettes. Zeitschr. f. wiss. Zool., 36: 181-200.

MACBRIDE E. W., 1893. The development of the genital organs, ovoid gland, axial and aboral sinuses in Amphiura squamata; together with some remarks on Ludwig's haemal system in this Ophiurid. Quart. J. Micr. Sci, 34: 129-153.

MacBride, E. W., 1914. Text-Book of Embryology. Vol. I. Invertebrata. Macmillan and Co., Ltd., London, pp. 498-501.

METSCHNIKOFF, E., 1869. Studien über die Entwickelung der Echinodermen und Nemertinen. Mem. d. l'Acad Imp. des sci., St. Petersbourg, 7e ser., 14: 8, pp. 1-73.