236 W. HAEOLD LEIGH-SHARPE 



CHIMAERA MIRABILIS 



A male and a female of this small species, each measuring 77 

 cm., were examined from the west coast of Ireland. They rival 

 Chimaera monstrosa in length on account of their extremely 

 long tails. They differ from that species in the following par- 

 ticulars: The anterior claspers have five spines on their mor- 

 phological inner border; their pouch is more widely open and set 

 at a slightly oblique inclination to the animal's axis. The 

 posterior claspers are small and their division into an external 

 and an internal radius does not take place until half way down 

 their length. They are slightly grooved, and approximation of 

 the radii forms a narrow tube as in Chimaera colliei, but the 

 denticles are but small. The apopyle is half way along the in- 

 ternal radius and no cavity leads into it (fig. 15). There are 

 neither anterior claspers nor their pouch present in the female. 

 The frontal clasper of the male is small. 



RAIA 

 type: RAIA CLAVATA 



The thornback 



How far various species of the same genus differ from one 

 another must form the subject of a future memoir; meanwhile, 

 no two genera could present more differences than the two types 

 of Raia here discussed: R. circularis (Memoir I, p. 260) and R. 

 clavata. Unfortunately, erection is not the same in the two 

 cases, for, while in the former it consists in the diametrical expan- 

 sion of a soft clasper by a suffusion of blood, here it is effected 

 by the unfolding of the clasper edges and the protrusion of 

 complicated structures by muscular contraction, from the 

 position of rest shown in figure 19A to the condition shown in 

 figure 16. The clasper gland, though similar in structure, is 

 situated more posteriorly in the lobe of the pelvic fin, and its 

 duct, really that of the containing sac, is not carried down the 

 clasper as a closed tube to open posterior to the hypopyle, as in 

 R. circularis, but debouches at the apopyle, as in Torpedo, Try- 

 gon, etc. (Memoir IV). A deep sentina is present as in Rhino- 



