Holt and Caldeewood — Report on the Rarer Fishes. 453 



is accompanied by a steady increase in the dimensions of the various parts, and 

 that in no particular does any sudden proportional variation take place. Only 

 one exception appears in column D (13-4 cm.) where the greatest diameter of 

 eye shows an increased measurement when compared with the larger specimen C 

 (14'6 cm.), and the same measurement as the much larger specimen B (16 cm.). 

 In this particular specimen, however, the membrane of the eye, and the muciferous 

 cavities of the head, show very decided evidence of shrinkage, and we are inclined 

 to consider that, if indeed the increased measurement is not due to an individual 

 peculiarity, it may be explained by the shrinkage of the outer membrane. 



Fins. — In Giinther's description of this species* no variation is shown in the 

 fin-ray formula except with regard to the anal fin, which, on account of the 

 uncertainty which often may occur as to whether or not the entire caudal 

 termination is present, can readily be understood, especially in a species where 

 most of the examples procured have been of small size. 



In seven specimens examined by us with regard to the fins, a certain variation 

 takes place, and we have therefore shown it in our fin-ray formula at the 

 commencement of this description. The details are as follows : — 



Pectoral, 18 Pelvic, 7 



19? „ 7 



18? „ 7 



20 „ 7 



18 „ 7 



,. - „ 7 



20 7 



Johnson {loc. cit.), describing some specimens taken at Madeira, gives the 

 number of fin-rays in the second dorsal as 98, and in the anal 110. His largest 

 specimen was 13^ inches in length, or 4 inches longer than the largest specimen 

 in the above Table. Giinther gives 75—86 as the numbers applicable to the second 

 dorsal. 



Abdominal Viscera. — On opening the abdominal cavity, the oval depression is 

 seen to be the inferior surface of a gland-like body lying embedded in the 

 abdominal wall. It is flask-shaped, and perfectly black in colour. The neck of 

 the flask forms a canal which runs directly backwards along the inferior surface 

 of the abdomen, in the middle line, until it comes in contact with the opening of 

 the rectum, to which it has a fibrous attachment. A probe can readily be passed 

 along this canal from the gland-like body, but fails to find free access to the 

 rectum. In some specimens of M. laevis, trawled at night, a highly luminous fluid 

 was observed to issue from the vent, or from its immediate neighbourhood. No 



* "Challenger" Reports, vol. xxii., p. 128. 



