\ 



AMERICAN JOURNAL 95 



the sight, in the words of Van Beneden, the describer of Crepina, 

 and a well known student of the Annelids and Pohjzoa, is 

 enough " to drive the very idea of a Polyzoon far away" !'*' 



To conclude, it is impossible to avoid the impression that in 

 hastily referring the Brachiopods and Polyzoa to the Annelids, 

 Mr. Morse has judged the case on inadequate grounds, and from 

 the evidence before us it is not unsafe to predict that they will 

 remain in the future as in the past, unmolested among the 

 Molluscoidea, with their nearest allies the Tunicates. 



The recent observations of M. E. Deslongchamps on the 

 spiculae contained in the mantle and circulatory system of most 

 of the genera, go far toward proving the erroneous nature of the 

 homologies which have been drawn between the calcareous sup- 

 ports oi Thecidium and the apophyses of other forms of Brackio- 

 poda. This is elsewhere discussed. 



I have preferred using the terms neural and h£emal to indicate 

 the difl'erent valves, rather than the appellations ventral and 

 dorsal, which can hardly be applied to the shells of this group. 

 I have considered the pedunculated extremity of the shell as the 

 posterior, and the opposite end as the anterior portions of the 

 mollusk. 



In the details of the apophyses, I have used terms whose 

 meaning is sufficiently evident ; dividing them into the crura, 

 hcemal processes, neural processes, lateral loops, neural loop, septal 

 processes, lateral processes, septum, &c., according to their rela- 

 tive position with regard to the shell, as will readily be under- 

 stood. 



The nomenclature of the figures is essentially the same as that 

 of Woodward's Manual, in which most of them originally ap- 

 peared. 



As no list of the recent species of Rliynclionella has been 

 lately published, I have added one, with appropriate references, 

 for the convenience of students. 



* Van Beneden, " Notice sur un Annelid" &c., Bull, de 1' Ac. Royale de 

 Belgique, 2d. Series, V, 1858, p. 4.57. 



Note. — I would add, that so far as I have carried my dissections of 

 Lingula anatina, the results obtained agree entirely with those of Mr* 

 Hancock, in his magnificent paper on the organization of the Brachio- 

 poda ; which stands unsurpassed in the annals of the comparative ana- 

 tomy of invertebrates ; and, while some of the surmises put forth in it 

 have not been confirmed by further researches, yet in the laborious ac- 

 curacy of the dissections it may ever serve as a model to students. 



