Reference : Biol. Bull., 140: 84-94. (February, 1971) BIOLOGY AND LIFE HISTORY OF THE NUDIBRANCH MOLLUSC, CORYPHELLA STIMPSONI (YERRILL 1879 1 M. PATRICIA MORSE Marine Science Institute, Xortlicastcrn University, Xaluint, Massachusetts 01908 Yerrill (1879) originally described Coryphella stiinpsoni from Eastport, Maine and in 1880 reported its range from Massachusetts Bay to Halifax, Nova Scotia. Bergh (1885) recorded the morphology of C. stiinpsoni based on a preserved specimen collected in Nova Scotia and sent to him by Verrill. Krause (1892) and Knipowitsch (1902) found C. stimpsoni in Northern Europe and the latter described a new variety based on radular variation. In October, 1968 and 1969 a large number of Coryphella stimpsoni were en-countered moving over mud flats in what appeared to be a mass migration at the Moosehorn Wildlife Refuge, Edmunds, Maine. The nudibranchs were taken to the Northeastern University Marine Science Institute where further observations were made which are reported here. MATERIALS AND METHODS Observations and measurements were made on living animals whenever possible. Radular mounts were prepared utilizing Turtox CMCS and Gomori trichrome stain ; the latter one clearly differentiated the teeth from the radular membranes. At the Marine Science Institute, the specimens were maintained in plexiglass tanks. Egg masses were isolated in glass dishes on the water table. Newly hatched specimens were relaxed in 5% M g Cl 2 , fixed in Hollande's fluid, sectioned and stained. Adult specimens were relaxed in 8% M g CL, fixed in Hollande's fluid and W c /c formalin. Representative specimens have been deposited at the U. S. National Museum (Smithsonian) and in the Mollusk Department of the Museum of Comparative Zoology at Harvard University. RESULTS Description of the adults Living specimens ranged from 13-20 mm in length and the foot measured 4.5-5 mm in greatest width. The cerata are evenly distributed in two longitudinal bands on the dorsal surface and extend anteriorly beyond the position of the paired rhinophores. The cerata are largest medially and decrease in size while increasing in number toward the lateral margin of the mantle (Fig. 1). The head is large and forms a characteristic trefoil due to the presence of large rounded lateral lobes. The color of the head and tentacles is an opaque white, identical to the body color. The smooth oral tentacles are slightly longer, taper more abruptly, are wider at the base and narrower at the tip than the rhinophores. During movement, the tentacles are continually brought in contact with the sub-84
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