564 MR. T. GOODEY. OX THE SKELETAL [Mar. 15, 



k. Externals. 



Compared with the pectoral fins of the same specimen the 

 pelvic fins and mixipterygia are quite large. As mentioned 

 by Giinther (14) and as will be seen from the measurements 

 given above, the edges of the pelvic fins reach to within a com- 

 paratively short distance of the posterior ends of the appendages. 

 On the dorsal side of each appendage, bounded by muscles, is the 

 channel, which, toward its posterior end, becomes somewhat 

 lateral in position and is bounded here by the knife-eclged, 

 movable terminal cartilages T.d. and T.v. In a ventral aspect 

 the most prominent feature of the appendage is the glandular sac 

 and compressor muscle, covered with loosely fitting soft skin. The 

 sac does not extend anteriorly as far as the point of attachment 

 of the basipterygium to the pelvic girdle. It may perhaps extend 

 farther forward in more mature and larger specimens, or again it 

 may be that the specimen under consideration was not taken at 

 the period of sexual maturity, at which time the glandular sac 

 enlarges considerably in most Elasmobranchs. The skin covering 

 the sac and the terminal parts of the appendages is very soft and 

 is entirely free from dermal -spines. 



1. Musculature. 



In the following description I am adopting the nomenclature 

 used by Huber (20), which differs somewhat from that used by 

 Jungersen (21) ; more particularly in regard to the muse, extensor 

 of the latter. This muscle Huber divided into muse, flexor 

 extermis and muse, flexor interims, both of which he found in all 

 the examples on which he worked. I have found both also in 

 Chlamydoselachus. 



Muse, adductor, A. — This is comparatively small, a,nd has its 

 origin in the posterior border of the pelvic girdle, to which it is 

 attached by a strong ligament. It is partially overlaid by the 

 muse, flexor internus, and is inserted on the inner distal end of 

 the basipterygium. 



Muse, flexor extemus, Fl.e. — This originates chiefly with A, 

 and on the inner surface of the latter, from which it later on 

 separates. It is inserted on the proximal end of the muse, 

 dilatator and also on the whole of the proximal side of the 

 radial /3. 



Muse, flexor internus, Fl.i. — This has its origin on the inner 

 side of the basipterygium and is inserted on the proximal end of 

 the axial cartilage b. It is partially overlaid by the muse, flexor 

 externus. 



Muse, dilatator, D. — This is a large muscle wrapping the inner 

 and ventral surfaces of the axial cartilage b. It has its origin on 

 the proximal end of b, partly beneath' the. radial" jS, and is inserted 

 chiefly on the inner side of the same cartilage and on the 

 terminal cartilage T.d. It is also inserted to a much smaller 



