(I) Rhabdopleura. 



(II) Enteropneusta. 



(III) PJwronis. 



(IV) other animals. 



(I) Relations to Rhabdopleura. 



The researches of Fowler (92, 1,2; 04) and of Schepotieff (04) appear to me to 

 have demonstrated the correctness of the opinion expressed by the earliest investigators of 

 Cephalodiscus (M'Intosh, 87, pp. i, 32) that this animal is most nearly related to Rhabdopleura. 

 It is true that Fowler's results have been criticised by MM. Conte and Vaney (02) whose 

 conclusions have been published in the form of preliminary communications only. They have 

 been replied to by Fowler (04), but in the absence of the full memoir it is difficult to do 

 justice to the results of the French authors. The most important of their statements are perhaps 

 {a) that the body-cavity of Rhabdopleiira is not subdivided in the way characteristic of Cepha- 

 lodiscus; (b) that the testis has the form figured by Lankester (84, PI. XL, fig. 7) and that 

 it is formed from "une differentiation de I'extremite anterieure du pedoncule"; while the ovary, 

 described for the first time, is formed at the expense of the axial part of the peduncle, "mais 

 "a I'extremite opposee a celle 011 se developpe le testiciile"; (<) that collar-canals do not exist; 

 [d) that the notochord is merel)- the anterior part of the peduncle ; [e) that Rhabdopleura is 

 related to the Entoproct Polyzoa. 



The denial of the existence of the notochord, collar-canals and subdivisions of the body- 

 cavity is directly opposed to the results of Fowler, which appear to me to be reliable. I have 

 satisfied myself of the existence of the collar-canals at least, although I have had but little 

 material suitable for the examination of the structure of Rhabdopleura. Schepotieff (04) with 

 a knowledge of the statements of Conte and Vaney has, moreover, confirmed Fowler's results 

 in essential particulars, although he considers (p. 16) that the cavity of the two arms is not 

 continuous with that of the rest of the collar, and he alludes to the collar-canals (p. 15) as 

 "Nephridien". One point in the results of MM. Conte and Vaney is of special interest in 

 connexion with Cephalodiscus, namely the account of the gonads and particularly of the testis. 

 The statement that that organ is a differentiation of the axial part of the stalk may well have 

 some relation to the phenomena which I have described in C. sibogae. I do not profess to 

 understand their statements with regard to the ovary. 



If Fowler's results, confirmed by Schepotieff, may be accepted, it seems to me hardly 

 possible to doubt that Rhabdopleura is the nearest known ally of Cephalodiscus. The subdivisions 

 of the coelom and the corresponding external segmentation, the relations of the arms to the 

 collar-region, the structure of the stalk, the phenomena of the budding, the existence of the 

 notochord and collar-canals, all these form a cumulative body of evidence ') which appears to 

 point conclusively in that direction. 



i) In the copy of his paper which M. Schepotieff has h.ad the kindness to send me, he has added the following MS note 

 'Ein Paar dorsalen Poren am Kopfschild warden neulich gefiinden". 



SlHOGA-EXrEDITIE XXVl/'/V. 15 



