IO 



O and R. Hertwig (1879) published an account < » i" tin- arrangement of the mesenteries 

 which did not differ materially from ihat of Haime, but in ;i postcript, written after the 

 appearance of von Heider's paper, the) added .1 confirmation <»t" his results. 



All these observations wen- made on ( '. memóranaceus, for although the Hertwi 

 mention ( '. as having been included within the scope of their observations, it would 



seem that their anatomical studies were confined to the first named species. In 1890 I showed 

 th.it in C. amei . while the general plan of the mesenteries was 1 i entially the same as 



in ( '. membranaceus , there were differences in the details. Thus I noted, as Haime had done, 

 that shorter fertile mesenteries alternated with longer ones, and also that short sterile mesenteries 

 alternated with both series of fertile ones. The short directives and the continuous septa were 

 served, but these latter wen- not the only mesenteries which reached the aboral pole 

 of the body, several of the longer fertile ones having a similar length. 



In 1891 Faurot, trom his studies on C. memó,ranaceus, brought into prominence an 



important characteristic in the arrangement of the mesenteries of that form, namely, that as a 



It of the alternation of sterile and fertile mesenteries and of the alternation ol short and 



fertile ones, there was in reality an arrangement of the deuterocnemes, at least, in quar- 



, or as Fauroi preferred to term them quatrosepta. The mesenteries in the vicinity ol 



glyph were found to present an arrangement different from that of the more latei. il 



quartettes, and while at first Faurot regarded the four mesenteries on either side of the mid- 



ventral line as p-presenting an aberrant qnartette, in his later paper (1895) he places only 



the three ventral couples in a group apart and begins the enumeration of the quartettes with 



tlv fourth couple. In making this change, which cannot be regarded as a happ) one, Faurot 



apparently inlluenced 1>\ the views of van Beneden (1891) concerning the si^niticance of 



ianthid protocnemes, and the latter author in his account of the arrangement of the 



in C. lloydii (1898) also regards the fourth couple from the mid-ventral line as the 



inning of the first quartette. 



I have given above what seem to me to be good reasons lor regarding the fourth 

 couple as belonging to the same series as the more ventral couples; for regarding, in other 

 words, the four ventral couples as forming a protocnemic group, and all the other couples .1-. 

 forming a deuterocnemic group. and on this ground alone it seems t<> me preferable to regard 

 the quartetti beginning with the fifth couple of mesenteries, that is to say, with the first 



deuterocnemi quartette arrangement, under such a system of enumeration. would be 



characteristic of thi 1 rocnemes, leaving the protocnemes as a group apart. 



The Prol mie Mesenteries. The four couples of mesenteries which represent 



the protocnemes in tlv adult have a very similar arrangement in those species in which the 

 arrangement has heen longest known, as, for example, in C. membranaceus (Haime, [854; von 

 79; Faurot, . C. lloydii van Beneden, 1898) C. verrillii (Kingsley, 19 



I , that ihc- term that 



vin his papci "ti Vl RRI1 



>l the specific name by I ' ■, 1 on 



i erlooked the 



