171 



as in 0. pusillus, with small obtuse, interlacing branches at the slightly 

 swollen end; there is no median process (Fig. 95). — In the posterior part 

 of the body some comparatively large grains, evidently pigment cells, 

 are seen. 



In the specimen figured the hydrocoel has not yet begun to form the 

 primary lobes; this is, however, the case in other specimens, and as the 

 arms are not longer in these than in the one figured, it seems beyond 

 doubt that the arms will not be much longer in the fully formed larva. 



Fig. 95. Skeleton of Ophiopluteus diegensis. ^^"/i- Letters as in fig. 85. 



A number of specimens were found in a plankton sample from San Diego, 

 California, 7/IX. 1915. 



This species bears so close a resemblance to Ophiopluteus pusillus, espe- 

 cially species b, that the suggestion lies at hand that it is really related 

 to it, in spite of the apparently essential difference in the structure of the 

 body skeleton. On the other hand, it also bears some resemblance to 

 Ophiopluteus fusus. At our present state of knowledge it is impossible to 

 ascertain which is the correct reference, especially so long as we do not 

 definitely know the value of that conspicuous character of the body 

 skeleton, the simple or the compound structure. 



Ophionereis squamulosa Koehler. 



PI. XXXI, Figs. 1—6. 



During my stay at Tobago, B. W. 1., with the Carnegie Expedition I 

 had the good fortune of seeing (on the 13th of April 1916) a specimen of 

 this species discharge its eggs, which were at once fertihzed, a male speci- 



22* 



