OF CONCHOLOGY. 57 



12. Bristles or sttce in larval worms and Brachiopods. 



I have already stated that the very young of Terebratula are 

 without any setae, as well as the adults of many genera of Bra- 

 chiopods, and hence no systematic value in relation to the posi- 

 tion of the class can be assigned to such features. 



13. Close resemblance in nearly every point of their structure 

 (of Crepina and Phoronis) to the hippocrepian Polyzoa. 



I have already shown that this so-called "close resemblance" 

 is confined to the fact that both have a crown of tentacles, and 

 is otherwise entirely fallacious and non-existent. 



14. Sand tube of Lingula (—Grlottidia) differing in no respect 

 from the sand tubes of neighboring Annelids. 



An examination of this "sand tube " shows that it differs from 

 those of Annelids in being merely sand adhering to a flocculent 

 mass of mucus surrounding the peduncle, without firmness, per- 

 sistency or any particular shape ; and is, of course, formed in a 

 totally different manner from the tubes of any Annelid. The 

 colored blood noticed in this species is exceptional, but is a char- 

 acter of very slight importance from a systematic point of view. 

 (Cf. ante.) 



A few other statements made by Prof. Morse before the Bos- 

 ton Society of Natural History, Nov. 16, 1870, require notice. 

 After reiterating the statements which I have just reviewed he 

 calls attention to — 



15. Serial arrangements of setce and gill-lamina.' in Brachio- 

 pods as in Annelids. 



No serial arrangements of these organs (other than such as is 

 seen in the branchiae of Patella and various other mollusks) is to 

 be observed in any of the many Brachiopods which I have dis- 

 sected, nor does any such serial .arrangement as occurs in the 

 fasciculated setae of Annelids obtain in any Brachiopod. This 

 is a notorious and easily observed fact. 



16. Striated muscles absent in the Mollusca. 



This error is refuted in the same number of Silliman's Journal* 

 which contains Prof. Morse's communication. 



Transversely striated muscular fiber occurs in all the classes 

 included under the type Mollusca, except the Cephalopods, where 

 it will probably be found when carefully searched for. On the 



*Feb., 1871, p. 123. 



