rg ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 



tended to more species of the genus, and therefore the result as to comparison has only been slight. 

 The species show great differences that may easily be used diagnostically. The corresponding struc- 

 tures in the different species are easil)- pointed out; more difficult it is to work out the comparison 

 with the other Plagiostomes in a sure way. I hope, however, to have succeeded in this in the follow- 

 ing description of the species I have examined. 



Raja batis L. 



(PI. IV, fig.45-4S.) 



The appendices of the Skate are mentioned by several authors, who, however, have restricted 

 themselves to brief remarks of the outer shape and the size. This latter may in old males be so con- 

 siderable that the appendices may convey a notion of .Skates with three tails , or «Skate-Kings» 

 (Pontoppidan)'); lyillj eborg^) gives, in old males, the length to be between 1/4 and Vs of the total 

 length of the animal, and says that the appendages reach far behind the middle of the tail. I know, 

 however, no thorough representation of these organs or their skeletons). 



In a specimen of a length of i™ 26"" (2 ell Danish) the appendix has a length of 27,5'='" ■>). 

 The other measures were: 



From the fore edge of the slit to the end of the appendix 25 — 26"" 



The part free of the ventral 18"" 



The terminal part 13'='" 



The largest breadth (across the basis of the terminal part) 4='" 



The shape of the appendix is flattened, the contour clavate, the breadth increasing towards, 

 and culminating in, the big, ovate terminal part. The skin is naked in every place. The appendix- 

 slit in the free part of the organ is situated quite close to the lateral edge; in the part united with 

 the fin more towards the middle of the dorsal side; in front the slit is easily dilated, and a little- 

 finger may here be brought into the ventral glandular bag, the powerful gland of which may be 

 partly discerned through the skin; the rest of the slit until the terminal part is certainly open, but 

 on account of the stiffness of the marginal cartilages it can only be ver)- little dilated; in the term- 

 inal part, however, dilation may easily take place, especially if the end of the appendix is bent ventro- 

 medialh'. In the terminal part the skin forms on the ventral side a large, soft lip, closing together 

 with the dorsal lip, which is supported by .skeletal parts. If the soft lip is thrown back, its inner, 

 bluish-red mucous membrane is seen, as also a large skeletal piece (T^) with sharp, indented outer 

 edge; it is, however, quite covered by the mucous membrane, which on the dorsal side of the piece 



■) See Kroyer, I.e. p. 993. 



2) 1. c. p. 590. 



3) The Ray mentioned by Joannes Battarra in Atti dell' Ace. deUe scienze di Siena, Tonio IV, 1771, p. 553i the 

 appendix-skeleton of which he draws in fig. I, must be the Skate, or at aU events a nearly allied species (according to Giglioli 

 [teste Lilljeborg] the Skate is not found on the coasts of Italy (?)). Davy I.e. p. 145 mentions the glandular bag and its 

 large glandular body, its secretion etc. 



4 In two skeletons of ventrals belonging to the Zoological Museum the appendices have a respective length of 

 41cm and 38cm. 



