142 NEW INVERTEBRATA FROM COAST OF CALIFORNIA. 



Puget Sound. The number of branchial appendages is 

 the same as in Cooper's specimens and less than in those 

 of Gould. 1 



Mr. A. Agassiz has kindly loaned me drawings of an un- 

 identified Nudibranch taken by him in 1859 at Port Town- 

 send, Washington Territory. One of these represents a 

 side view (PI. vi, fig. 2), another a dorsal and a third the 

 head from below looking into the mouth. The last men- 

 tioned shows the two rings of cephalic tentacles and the 

 slit-like character of the mouth in addition to the features 

 already mentioned. From the resemblance of these figures 

 to those given by Gould I had referred them to Chiorsea. 



The main anatomical features of Chiorsea are given by 

 Gould and Cooper, whose accounts differ only in subordi- 

 nate particulars. In the main, my observations resemble 

 theirs, only differing in details. No one has yet discussed 

 the affinities of Chiorsea with other genera, although new 

 genera, closely akin to it, have been described. It may 

 not be out of place to call attention to certain affinities of 

 this rarely 2 mentioned animal. Its systematic position is 

 near Melibe, of which we have a species M. rosea Rang, 

 from the Cape of Good Hope, and M. fimbriata described 

 by Alder and Hancock. Kalaart's species, M. viridis, 

 seems different from either. It is more closely allied to 

 Tethys which is not yet known to occur in the Pacific. Its 

 remarkable differences from either Tethys or Melibe, en- 

 title it to membership in a new family, the Chiorseadae, in 

 which it stands alone, but if we follow Alder and Han- 

 cock's classification it would be an aberrant member of the 

 Tethydse. 



1 Cooper justly suspects that this difference may arise from immaturity. 

 Gould's specimens were five inches in length; Cooper's, two and three-fourths 

 inches. 



*This genus is not mentioned in several monographs of the Nudibranchs and 

 its systematic position has remained hitherto undetermined. 



