MISCELLANEOUS. 257 



dual formation at certain seasons of what seems an ovarium. A quan- 

 tity of green spawn once appeared in a vessel containing a specimen in 

 the beginning of June. 



This animal lurks in shells, or under them, protruding the head, 

 which, like that of the Nereis, is waved from side to side. Probably it 

 dwells in mud, by which it is generally much disfigured, but which leaves 

 it clean and translucent when washed away. I could never discover any 

 tube or shelter of its fabrication. It is impatient of light. 



This animal is neither rare, nor difficult to be preserved. 



Its gelatinous consistency is best seen on pouring off the water, 

 when it appears smooth and shining. 



PLATE XVIII. 



FIG. 10. Siphonostoma gelatinosa. 



11. Section of the body, enlarged. 



12. Head, enlarged. 



4. PHERUSA MULLERI. Plate XVIII. Figs. 5, 6, 7, 8, 9. 



A distinguished naturalist, Otho Frederic Miiller, has named the 

 subject of this brief notice Amphitrite plumosa. M. de Blainville consi- 

 ders it as bordering on the Spio ; but Oken institutes a genus Pherusa 

 for its reception. 



Certainly the subject in question has none either of the principal or 

 subordinate features of the Amphitrite, and it is still more unlike the 

 Spio. In the reference which I have seen to Oken, a clay tube is ascribed 

 to it for a dwelling ; but among a number of specimens taken from dif- 

 ferent situations, nothing of the kind has ever occurred to me ; neither 

 has the animal testified a disposition to occupy any tube, though such 

 might be inferred from its organization. 



The body of this creature is of vermicular form, crowned by a head 

 or anterior extremity of complex structure. The whole extends three 

 inches and a half, by above three lines in thickness. It is quite round, 



2K 



