ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 



57 



forms a great many transverse, soft, vascular folds (see fig. 24 in the text, />/). If the terminal part is 

 more opened, the walls of the appendix-slit are seen; they are very curiously formed, covered with a 

 mucous membrane, and their folds and pockets supported In- 

 different skeletal pieces. Besides what has been mentioned, we 

 find on the ventral side a firm fold with a porous edge, da, 

 reaching into the proximal part of the slit, and a process (7r' 2 ), 

 with a loose, soft covering, and supported by skeleton; laterally 

 of this process is found behind a deep recess or pocket, Lv. On 

 the dorsal side are seen two recesses, the foremost one (Ld) 

 very deep, and separated from the appendix-slit by a lamella 

 supported by skeleton; the hindmost one (Ld') is less deep; finally 

 is seen a process ( Tzi), enclosed in a soft membrane, which process 

 is laid against the above mentioned one on the ventral side of 

 the slit. The real continuation of the appendix-slit runs between 

 these two processes, as indicated by the sound in fig. 24 1 ). 



The skeleton. Between the basale and the appendix- 

 stem are found two pieces , b 1 , b 2 , the latter longer than the 

 former; b t bears the six hindmost rays, b 2 , as usual, none; with 

 the dorsal and lateral edge of b z is connected a long, plate-shaped 

 /?, distally articulating with the appendix-stem b almost beside 

 the articulation between this latter and b 2 . 



The appendix-stem is long, about twice as long as the 

 basale -\- b l 4- b 2 ; behind it becomes by and by dorso-ventrally 

 flattened, especially in the terminal part, where its outer end is 

 quite flattened, thin, and rounded. As is usually the case, the 

 calcification ceases in the terminal part; in the long part corres- 

 ponding to the style is however found on the medial edge a 

 strongly calcified region projecting in a somewhat bump-like 

 manner (x in fig. 45, 47). The marginal cartilages are long and 

 hard, and are for a long way rather closely joined with their 

 edges; distally they separate; the dorsal one begins before close 

 by the articular surface between [i and /;, but distally it does 



not reach as far out on the stem as the ventral one, which in return does not reach so far proximally 

 as the dorsal one; thus an open space is found proximally, where the glandular bag joins in, and 

 where its foremost, dilatable outlet is situated. The dorsal marginal cartilage sends forth distally a 



ITd 2 ) 



Fig. 24. Raja batis. The terminal part 

 of the right appendage, from the dorsal 

 side, strongly dilated (much reduced). 

 A sound goes through the bottom of the 

 appendix-slit, vl the soft, ventral dermal 

 lip; T^ the terminal piece T i covered by 

 mucous membrane with the dermal leaves 

 bl\ da a firm dermal fold, dotted with small 

 holes on the edge. Lv the ventral pocket, 

 Ld, Ld' the two dorsal pockets ; d, dl the 

 dorsal lip with the enclosed skeletal parts 

 d and Td 2 \ Rd' a dermal fold, supported 

 by a plate-shaped prolongation of the 

 dorsal marginal cartilage; Ti\ Tv 2 dermal 

 projections supported by the skeletal 

 parts marked with the same letters. 



M In specimens with quite short, undeveloped appendices, shorter than, or of an equal length with, the fin-mem- 

 brane (the free part from 2,5 -3,5cm j n length), we, as might be expected, do not find much of these elaborate structures; in 

 such young appendices with all parts still soft the appendix-slit is easily opened and quite spread, and then the walls of 

 the slit are seen to be smooth and simple, upon the whole without recesses or folds, also in the terminal part; one strongly 

 pronounced dermal fold is however seen along the ventral lip; the inner, already plate-shaped edge of this fold represents 

 the spongy-porous dermal fold (da) in the adult, and in the lateral part of it the large skeletal part T 3 will develop. 



The Ingolf-Expedition. II. 2. ° 



