52 



49 



9-5 



9 



7 . 



7 



8 



8-2 



2-5 



2-7 



10-5 



9 



3-8 



3-8 



5 



5 



7-8 



6-5 



758 Memoirs of the Indian Museum. [VolV, 



Measurements in millimetres. 



Total length excluding length of caudal 



Length of head ... 



Height of head near occiput 



Width of head ... 



Length of snout ... 



Length of caudal fin 



Length of pectoral fin 



Length of pelvic fin 



Greatest height of body 



The new species differs from all the other known Indian species of the genus in its small 

 size, in the fewer number of rays in the vertical fins and in having different proportions. 



Family BOTHIDAE. 



Genus PSEUDORHOMBUS Bleeker. 



Pseudorhombus arsius (Ham. Buch.). 

 1878. Pseudorhombus arsius, Day, Pish. India II, p. 423, pi. xci, fig. 5. 



The four specimens of this species were collected from three localities, one from Pari- 

 kudh, two in Serua Nadi and the remaining one in the channel between Barnikuda and Sat- 

 para. The largest specimen is 24 cm. in length including the length of the caudal fin. 



There has always been a certain amount of confusion between this species and Pseudo- 

 rhombus russeUi (Gray), which was figured as Platessa russellii in the Illustrations of Indian 

 Zoology on plate 94 without any description. Subsequently Günther 1 described it from the 

 type and several other specimens from China, the East Indian Archipelago, Bengal and other 

 places. Day, 2 who had previously regarded P. russelli as distinct from P. arsius, in his 

 later work {ojs. cit.) considered the former to be synonymous with the latter. Several ichthy- 

 ologists such as Castelnau, 3 Macleay, 4 Klunzinger, 5 Boulenger 6 and Sauvage, 7 who came 

 after Day, recorded P. russelli from widely different localities without comment and without 

 any reference to P. ar sius. I have carefully compared Günther's description of P. russelli 

 with an original manuscript drawing of Buchanan's P. arsius. I am of opinion that the two 

 are identical, the latter representing an immature specimen, while the former is based on 

 an adult. Day has already shown the variation which the members of this species exhibit 

 as regards the number of fin-rays and scales along the lateral line. 



1 Günther, Cat. Brit. Mus. Fish. IV, p. 424 (1862). 



2 Day, Troc. Zool. Soc. London, p. 287 (1865) ; ibid., p. 523 (1869) ; ibid., p. 698 (1870). 



3 Castelnau, Proc. Linn. Soc. N. S. Wales III, p. 391 (1878). 



4 Macleay, ibid. II, p. 362 (1878). 



5 Klunzinger, Sitzungsb. K. Acad. Wiss. Wien LXXX, p. 406 (1880). 



6 Boulenger, Proc. Zool. Soc. London, p. 665 (1887). 



7 Sauvage, in Grandidier's Hist. Nat. Madagascar XVI, p. 473 (1891). 



