236 Records of the Indian Museum. [Vor,. XIII 



The Crustacea found in the Matlah River most strikingly 

 resemble deep-sea forms in their colour. Parapenaeopsis sculptilis 

 is uniformly deep red, while the Palaemonidae are of a milky 

 semitranslucency ' with red markings. In Palaemon mirahilis 

 red flecks or suffusions are found on the abdominal somites; in 

 Leander styliferus the tip of the rostrum and the extremities of the 

 telson and uropods are red. In L. tenuipes the mandibular region 

 is bright red and the rostrum dotted with carmine ; the lower 

 antennular flagellum is carmine at the base^ changing to deep 

 mauve nearer the tip ; there are red flecks on the abdominal somites 

 and the telson and uropods are deeply stained with bright red. 

 The eggs are gamboge or greenish yellow. 



The peculiar character of the Matlah fauna is at first sight 

 most forcefully brought to notice through the medium of colour, 

 and it is unfortunate that it is not possible to do justice to this 

 very striking feature by mere description. Several of the con- 

 stituent species, however, show in their structure also a remark- 

 able resemblance to deep-sea forms. The most notable instance 

 is perhaps the " Bombay Duck," Harpodon nehereus,^ which, with 

 its gelatinous consistency and large mouth with the lower jaws 

 loosely articulated and furnished with recurved teeth, exhibits 

 every characteristic of a deep-sea species. Harpodon nehereus 

 differs from all other forms found in the Matlah River in belong- 

 ing to a family (the Scopelidae) the members of which are almost 

 exclusively of abyssal or bathypelagic habitat ; other species of 

 the same genus are known only from considerable depths. The 

 peculiarity of H. nehereus lies therefore not in its structure, but 

 in the fact that a representative of such a typically deep-sea 

 family should occur in shallow water. The resemblance to abyssal 

 forms misled even so great an authority as Gunther ; for, in 

 reference to the two species of Harpodon known to him (one being 

 H. nehereus), he remarks '^both are evidently inhabitants of con- 

 siderable depths, and periodically come nearer to the surface." ^ 



Polynemus paradiseus is remarkable for the extreme length of 

 certain free pectoral rays and for the elongation of the upper and 

 lower caudal roys. In general appearance it is not dissimilar to 

 deep-sea Scopelids of the genus Bathypterois, in which both these 

 modifications occur. The eyes in Bathypterois are small and some 

 of the species are probably quite blind ; in P. paradiseus the eyes 

 are small and covered by skin. 



In a number of the fish found in the Matlah River the body 

 tends to become attenuated posteriorly. This feature, which is 

 also found in abyssal forms, reaches an extreme development in 

 Coilia dussumieri, a species which bears a strange resemblance to 

 deep-sea fish of the genus Macnirus. 



i This milUy lint is also found in the bottom-Hving Medusa, Asennthia pis- 

 cat or is. 



2 Dr. Chaudhuri informs me that Hamilton- Buchanan must have adopted the 

 specific name of this fish from the Bengali term nihnde, meaning " boneless." 



2 Gunther, Study of Fishes, p. 584 (1880). 



