I 1 



(I) Rhabdoplcura. 



(II) Enteropneusta. 



(III) PJioronis. 



(IV) other animals. 



(I) Relations to Rhaódopleura. 



The researches of Fowler (92, i , 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 anima! is most nearly related to Rliabdopleura. 

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

 conclusions have been pubhshed in the form of preliminary Communications only. They have 

 been replied to by Fowler (04), bnt 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 

 [d] that the body-cavity of Rhabdopleitra is not subdivided in the way characteristic of Cepha- 

 lodiscus-, [b) that the testis has the form figured by L.\nkester (84, PI. XL, fig. 7) and that 

 it is formed from "une différentiation de l'extrémité antérieure du pédoncule"; while the ovary, 

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

 "a l'extrémité opposée a celle oü se développe Ie testicule"; (r) that collar-canals do not exist; 

 {d) that the notochord is merely the anterior part of the peduncle ; [e] that Rliabdopleura 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 

 sati.sfied 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 Rliabdopleura. Schepotieff (04) with 

 a knowledge of the statements of Conté 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 coUar, and he alludes to the collar-canals (p. 15) as 

 "Nephridien". One point in the results of MM. Conté 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 différentiation 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 had the kindness to send me, he has added the füllowing MS note 

 'Ein Paar dorsalen Peren am Kopfschild wurden neulich gefunden '. 



SIBOGA-EXPEDITIE XXVI /'W. IS 



