j , ON THE APPENDICES GENITALES (CLASPERS) IN THE GREENLAND SHARK 



other muscles are found, more especially belonging to this organ, it being inside the skin quite 

 surrounded by muscles except the terminal part. In this muscular system may naturally be distin- 

 guished between: i) The muscles of the chief piece, and 2) those of the glandular bag. 



1) The first part (pi. V, fig. 58— 62, D) is composed of one single muscle wrapping in a cloak- 

 like manner the whole of the chief piece from the dorsal marginal cartilage to the ventral one, 

 and to the rounded edge formed by the appendix-stem itself along its lateral surface above this 

 short marginal cartilage; the part of the chief piece situated between these bounds, the lateral 

 surface is for the greater part covered by the muscles of the glandular bag (see fig. 1). The 



large muscle D is thickest along the medial side of the 

 appendix, and is chiefly composed of longitudinal fibres 

 arising from the whole length of the chief piece; from 

 the foremost part of this, below the knee , arise some 

 specially powerful bundles, and consequently this part 

 of the surface of the skeleton is very rugged; also from 



the lateral edges arise numerous fibres and bundles, 

 Fig. 1. ft ' 



Part of a transverse section through the appen- and distally several bundles come from the covering 



daee of the Greenland Shark (about 26"™ behind • , , TT <■•_ /- > /-« -,• . .-, r 



" , ' ,. , , aponeurosis a (see pi. V, fig. 61 . Corresponding to the form 



the beginning of the appeudix-sht). the appen- 1 x ° r ° 



dix-stem; D M. dilatator; E M. extensor; S M. com- of the appendix-stem this muscle tapers distally, and its 



pressor; af the appendix-slit; r a rav; // horny ... r ., . , , - , , T . 



filaments hindmost fibres reach to the base of the style, it is 



inserted in the firm aponeurosis covering the marginal carti- 

 lages and the whole terminal part, and thus it acts on the style and the two terminal pieces Td and 

 Tv. In contracting it bends the style medially forward at an obtuse angle to the chief piece, where- 

 by the two terminal pieces are also moved; at the same time the thorn is erected on account of its 

 connection with the other terminal pieces, especially Tv, and stands out laterally; as a consequence the 

 distal part of the appendix-slit situated between these movable pieces, is dilated to a rather consider- 

 able degree. I therefore (like Petri) design this muscle as M. dilatator. 



2\ Among the muscles of the glandular bag I do not only class a) the muscles immediately 

 wrapping this organ, but also b) some portions (fig. 61, 62, S) arising from the hindmost rays, and 

 forming, in my opinion, with the glandular bag an insolvable whole, only artificially to be detached 

 from it. The glandular bag, as I understand it, has its origin from an invagination of the skin 

 into a muscular mass laterally covering the stem-skeleton in the appendix; by the further growth of 

 this invagination on to the ventral side of the fin part of the muscular mass was brought along as 

 a kind of wrapping of the bag and developing further together with it. Consequently this wrapping 

 cannot be regarded as dermal muscles but belongs to the skeletal muscles; it is also composed of quite 

 the same striated fibres as these; its original relation to the stem-skeleton may, in the fully developed 

 organ, be seen in the still existing attachment along the lateral surface of the appendix-stem (see the 

 transverse section, fig. 1 in the text). 



a. The glandular bag (pi. V, fig. 58, 60 S) is seen on the ventral side of the fin, where it 

 reaches forward covering a .smaller or larger part of the ray-muscles, according to the development 

 of the whole appendage; while in the youngest specimens it only reaches very little beyond the 



