ECHINODERMS. 69 



more irregular plates may have been derived. Color in alcohol, dull 

 yellowish brown ; tentacles yellowish white. 



Length of body, SO'""^ ; diameter, 24°^™; length of tentacles, S'"'". 



Kerguelen Island, twelve fathoms, January, 1875 (No. 214) ; Dr. J. H. 

 Kidder. 



ECHINOIDEA. 



Hemiaster coedatus, Verrill, s. n. 



Two quite distinct forms, which, for reasons given below, I believe to 

 be the males and females of one species, occurred together in about 

 equal numbers. The specimens believed to be females have very deep 

 lateral ambulacral grooves and large genital openings; in nearly 

 every specimen several young ones,* varying in size, were found in the 

 ambulacral grooves, held in place by the convergent spines of the bor- 

 ders, which meet across the grooves and interlock. Two of these speci- 

 mens, on dissection, proved to be females. Those supposed to be males 

 have much shallower ambulacral grooves and differ somewhat in form. 



The form of the body in the female is broadly cordate, depressed, with 

 a decided emargination in front ; vertically truncate and slightly emar- 

 ginate posteriorly ; broadest a little in advance of the middle. The 

 lower surface is convex and swollen, especially posteriorly; the sides 

 well rounded ; the interambulacral areas are swollen on the upper side ; 

 the abactinal area and the anterior ambulacrum are considerably 

 sunken ; the latter has two well-defined double rows of pores extend- 

 ing to the mouth. The lateral ambulacra are elliptical, rather broad, 

 obtuse at the outer end, and deeply sunken, the anterior ones broader, 

 but scarcely longer than the posterior ones, but those of the opposite 

 sides are not quite equal in size or form. Ovarial openings large, 

 usually but three, that opposite the right anterior interambulacrum 

 being abortive. Lower border of actinostome rather narrow, promi- 

 nent, and obtuse. Anal area ovate, the lower border rounded, the 

 upper narrowed, but scarcely acute. Peripetalous fasciole well defined, 

 bending upward but little on tne posterior and anterior interambulacal 

 areas, and jiassing nearly straight across the anterior ambulacrum, but 

 bending upward nearly parallel with the antero-lateral ambulacra, so as 

 to form a decided angle in the front part of the lateral interambulacral 

 areas. Subanal fasciole indistinct or wholly wanting. The tubercles of 

 the upper surface are small, crowded, and pretty uniform in size, ex. 



These young have been sent to Mr. A. Agassiz for examination and description. 



