ON THE APPENDICES GENITALES (CLASPERS) IX THE SELACHIANS. 2 l 



in the structure of these animals indicate that the Holacephales by no means occupy a primitive 



position among the Selachians. 



As to the skeleton of the ventral in the female, the basale (in Chimcera) has distally only one 

 small, tap-like joint, standing both for the piece 6 Z , and the appendix-stem {/>) in the male'). 



What has been given in the earlier literature as to the skeleton of the ventral appendages in 

 Selachians, is generally only isolated descriptions without any real understanding; only Gegenbaur 2 ) 

 and Petri have compared several forms, but neither of them has been able to recognise a 

 common type. Gegenbaur (I.e. p. 452) has interpreted the terminal pieces as modified rays, but mi 

 account of the circumstances in the Chimara, he indicates (p. 456) the possibility that they may be 

 parts separated from the stem-skeleton; he does not know the marginal cartilages, and he has considered 

 several early stages of the skeleton as definitive forms of it. Petri quite correctly has seen that 

 the terminal pieces and marginal cartilages - which latter, however, he has not recognised in all 

 the species he has examined -- are secondary structures, and have nothing to do with the rays; the 

 terminal stem-joint itself which I have called the appendix-stem (/>), he has interpreted correctlv in 

 Raja, but wrongly in Acanthias and ScylliumS) -- the only Sharks examined by him -- as well as in 

 Torpedo -f) (he has not examined Chimcerd). Some earlier authors have seen the piece /9 in some 

 specimens, while it by others has been overlooked, or at all events has not been mentioned. Only 

 Gegenbaur and Petri have sought its origin in a transformation of other skeletal parts of the 

 fin 5). Gegenbaur does not mention it at all in Raja, Carcharias and Scyllium b ) but in Heterodonttis 

 and Acanthias (I.e. fig. 16 and fig. 19, b), and in Chimcera (fig. 23 /); in the last named it is interpreted 

 as a ray, but in the two former as belonging to the stem-skeleton^); accordingly Gegenbaur has not 

 seen that in Chimcera it is the same skeletal piece as in the Plagiostomes. Petri thinks it to be a 

 coalescence of basal parts of rays, being of opinion that it bears rays in Acanthias and Torp 

 accordingly in his figures he marks it /. This supposition, however, is wrong 8 ); I never found rays 



M v. Davidoff (I.e. p. 473, pi. XXIX, fig. iS;S) thinks it only to be corresponding to it. Unfortunately I have onlj 

 had occasion to examine skeletonized ventrals of Chimcera y, in which this joint was wanting, so that the fin-stem consisted 

 only of the basale. 



2 \ Ueber die Modificationen des Skelets der Hintergliedmaassen bei den Mannchen der Selachier nn«l Chiniaren. Jen. 

 Zeitschr. vol. 5, 1S70, p. 452. 



3) In these Sharks Petri supposes the stem to end with a long and a short joint ; in Acani • as the shorl terminal 

 joint he has interpreted one of the terminal pieces (my piece Tv), in Scyllium the soft end-style. 



1 1 As to Torpedo see p. 49. 



51 Bloch, M. E. : Von den vermeinteii doppelten Zeugungsgliedern der Rochen und Have. Schr. der Berl G 

 schaft Naturf. Freunde, vol.6, 1785 {Raja c/avala [= radiata]); and: Von den verm, mannlichen Gliedern des Dornh 

 ibid, vols, 17SS, does not mention this piece in Acanthias, but in Raja, where he calls it: der vierte Knochen des Schenkels . 

 pi. IX, fig. 1, o. Cuvier (Duvernoy): Lecons d'anatomie comparee, 2 Ed., 1N46, vol s, p. 306, designate uni 



in Raja; the same appellation is used, likewise for Raja, by Moreau: Hist, nat des Poissons de la France, vol. I. [SSi, 

 p. 249. I have not found it mentioned by other authors. 



°) Of these three forms G. has only had quite young specimens, in which the secondary pieces had uol yet .level- 

 oped. The fault made here by G. viz. to consider this stage as the full-grown state, and accordingl) as an especiallj sin 

 form in these Plagiostomes, has already been corrected by Petri (Lc p. 293). It is t.> lie supposed, however, that the : 

 ,5 had been developed in all three forms, as in embryos of Acanthias of a length of only 15cm it is already 4111: and 



relatively as large as in the full-grown animal. 



7) I am quite unable to understand the place in question d. c. p. 451) in Gegenbaur; there is a n 



pancy between the letters in the text, and those in the figures, and also, 1 think, a change <>t' pieces, which makes the whole 

 coufused; so much, however, is certain that the piece which in the figures [6 an. I [9 is marked ' (1113 ; -t in 



Acanthias hear any ray; it never bears rays at all. 



8) For further details see under Acanthias ami Torpedo. When Petri, to support his con of this pieo 



