ON THE APPENDICES GENITALES (CLASPERS) IN THE GREENLAND SHARK. jo 



the question). Consequently I design the large chief muscle A as Miisailiis adductor (rf depressor) 

 pii/iKr (cf appendicis)^ the muscle E as Muse, extensor {appendicis)^). 



b. The ventral muscular system of the rays (fig. 58, 60, Ra) is comjjosed of distinctly separated 

 bundles of fibres, or independent muscles in number corresponding with the rays they follow; only 

 anteriorly the independence of the ra\-muscles, as mentioned above, is concealed bv coalescence with 

 the lateral bundles of Muse, adductor, coming from the pelvis. The ray-muscles originate on the 

 ventral surface of the basale and the piece b^_, and run lateralh- backwards in an oblique direction, 

 each following its ray, but without reaching the end of it; the\- only reach the horny filaments (the 

 two layers of which comprise a rather considerable part of the lateral ends of the rays| and here 

 pass into tendinous tissue. The hindmost ray-muscle is rudimentary; it does not originate on 

 the stem-skeleton, but on the last ray but two, and passes to the last but one and on to the fin- 

 membrane. 



2) The dorsal muscular sy.stem of the fin proper (pi. V, fig. 59 1 is composed of a) a super- 

 ficial part originating from the lateral muscles of the body, and b) a deeper-lying part originating from 

 the stem-skeleton. 



a) On a part of the body, corresponding in length to the connection between the body and the 

 fin, a system of distinct muscular bundles {O) originate in the aponeurosis covering the lateral muscles 

 of the bod}-, and run obliquely outward and backward to the horn\- filaments, where they pass into ten- 

 dinous tissue; thus their outward border corresponds to that of the ray-muscles on the ventral side, 

 being considerably distant from the ends of the rays. The hindmost of these bundles are directed 

 straight backwards, corresponding to the direction of tlie last of the rays. Furthermore from the 

 inner side, the side towards the muscles of the body, of the said s>-stem some bundles of fibres (C) 

 originate running obliquely backward and inward, and attached to the hindmost half of the basale 

 and to the dorsal piece /J; thus the whole system originating from the lateral muscles, is, as to the 

 hinder half, arranged in a feather-like or fanshaped way. 



b. Quite covered by the superficial layer just described the deeper layer of the dorsal ray- 

 muscles (fig. 59, Ra) is found. These muscles originate from the dorso-lateral side of the basale and 

 of the i^iece b^, as well as from /?, and are seen as distinct bundles corresponding in their number and 

 direction to the rays; they pass into tendinous tissue immediately before the lateral ends of the bundles 

 of the superficial layer, so that the latter reach a little way farther on the rays. However, these 

 two layers are not quite sharply separated, bundles of fibres from the superficial layer reaching to the 

 deeper, and connecting with it; on tlie hindmost fin-rays the bundles of the deeper layer cross those 

 of the superficial one, this latter spreading in a fanshaped way from the attachment to the body. 



II. Besides the described separate parts of the fin muscles connected with the appendix 



I) The muscle which in Acanlhias and other Selachians corresponds to the muscle A, is by Petri called: Flexor 

 pterygopodii\ but there are several objections to this name. Firstly, the muscle does not only act on the appendix, but on 

 the whole fin (it is also found in the female), and next it cannot well be called the flexor of the appendix, as it is more 

 properl}- to be regarded as the extensor. The flexion of the appendix is, I suppose, effected by means of the M. compressor 

 sacci, the muscle of the glandular bag (fig. 5S, 61, S], of which more hereafter, together with the muscular layer originating 

 on the body itself (fig. 59 and 6i, O). 



