172 



Memoirs of the Indian Museum. 



[Vol. II, 



Description of thk Types. 



In their gross structure the twenty-one specimens resemble one another and 

 conform to the original description of the genus ; they differ from one another in two 

 respects, firstly, in the breadth of the disk ; secondly, in the form and arrangement of 

 the dermal ossicles. The variation in the breadth can be studied by measurement 

 The length of each specimen was measured from the snout to the base of the tail fin. 



Broad 



Mediiun 



xooo 000x000 



A B 



00000 

 D 



P'iG. 7. — Proportion of breadth to length in 21 specimens of Malthopsis of communities A, B, C and 

 D: O = orderly, x = disorderly. 



The greatest breadth of the body was recorded as the distance between the most 

 prominent parts of the subopercular spines. Measurements were taken to the 

 nearest half-millimetre. The measurements are shown in the table at p. 176. The 

 breadths are also displayed as percentages of the lengths by lines of proportionate 

 length in text-fig. 7. This diagram shows that as regards breadth the specimens 

 fall into three groups, the members of which may be spoken of as narrow, medium 



