ON THE APPENDICES GENITALEvS (CLASPERS) IN THE SELACHIANS. 67 



to the lateral edge; the dorsal lip of the terminal jjart, also like that of the Skate, is along the whole 

 lateral edge supported by skeletal parts, while the ventral lip has a broad, soft edge covering the 

 skeletal parts (T-.^), and passing round to the dorsal side; if this dermal lip is thrown back, we shall 

 see, quite as in R. datis, a naked, cutting edge of a raised, winglike ridge on T^, running almost 

 throughout the terminal part. If this latter is opened still more, an almost complete conformit}- with 

 the features in the Skate will be seen; and thus it will be sufficient to point out the deviations. 

 These deviations are confined to the ventral side, and are chiefly as follows: i) the membrane cover- 

 ing the inner, dorsal surface of the piece T~ medially of the cutting edge, has very few and long, 

 obliquely situated, low dermal folds (that may easily be overlooked); 2) the fold i/a is shorter (short- 

 ened distally), softer, in the middle of its distal j^art it jirojects in a more tongue-shaped manner, upon 

 the whole most like that in /\'. radiata\ it is as in this and in batis without any inner skeletal support; 

 3) the two projections corresponding to the skeletal parts Tv and Tt'^, are somewhat longer, so that 

 the)- stretch distalh' over the opening of the \-entral recess which thereb\- gets a somewhat other 

 appearance than in R. batis. 



Raja circularis Couch. 



(PI. Ill, fig. 41— 44-) 



In old males the appendices are said to be somewhat more than '/j of the total length; in a 

 male of a length of 79,2''"', a breadth of 48,5'-''" they were 16,5'-"'" long '). 



I have onh- had the occasion to examine a dried skeleton in the Zoological Musemu; this 

 skeleton measures from the snout to the point of the tail 40"^'", across the pectorals c. 20'^"; the appen- 

 dix-stem has a length of 6,5''™, the terminal part of 3,7*^'", and a breadth of i'^™ on the broadest spot. 

 Between the basale and the appendix two pieces are found: b^ bearing the 8 (7) hindmost rays, and a 

 longer b^^ without rays, as well as a long, plate-shaped /?, broadest in the fore part. 



The ratio between the length of the appendix-stem and B -\- b^^ b^ is j/^ ; the rather narrow, 

 flat, soft terminal part is shorter than the calcified one. The dorsal marginal cartilage reaches forward 

 almost to the beginning of the stem, and ceases behind with a concave, oblique edge, the lateral 

 corner of which is situated much farther forward than the hindmost end of the ventral marginal 

 cartilage, which, as usual, does not reach so far forward. As in Raja batis and clavafa., the dorsal 

 marginal cartilage sends forth a long, thin, pointed, lamellar (calcified) prolongation passing in between 

 the terminal pieces (it is not seen in any of my figures). 



The number of terminal pieces is five, besides two dorsal covering pieces. One of these latter, 

 d^, I supi:)0se to be corresponding to the piece that in R. radiata has been marked in the same way; 

 it is long and narrow, spreads distally in a spoonlike manner, and the medial edge of the broader 

 part folds round the appendi.x-style towards the ventral side, where it is attached to the distal end 

 of the piece T'j (see fig. 43). The other covering piece, rt'j, is firmly connected with the dorsal surface 

 of the terminal piece Td^ (as is also the corresponding one in R. radiata) and is (as in this) distally 

 closely connected with the end of the apjjendix-style; it is rather thin and flat. 



■) Malm, K. V: Goteborgs och BohiisUins I'aima, tSyy, p. go6. 



9* 



