94 Records of the Indian Museum. [Voi,, X, 



Thor paschalis (Heller). 

 Plate I, figs. 6-10. 



1861. Hippolvte pasclialis, WeWcw S'W/.-h^r. Akad. Wiss. Wien, XLI \', 

 p. 276, pi. iii, fig. 24. 



1878. Thor floridanus, Kingsley, Bull. Essex Inst., X, p. 64. 



1S78. Tlior foi'idaiitis, Kingsley, Proc. Acad. Sci. Philadelph., pp. 7, 95. 



1879. TJior flori'Jniiits, Kingsley, ibid., p. 421, pi. xiv, fig-. 6. 



1887. Hippolyte pasclialis, do Man, Arch. f. Naturgesch.. LIII, i, p. 534. 

 1887. Hippolyte amhoiiiensis, de Man, ibid., p. 535. 



1901. Thor JloridiDiiis, Rathbun, Bull. l\ S. Fish Comni. for 1900, 11, 

 p. 116. 

 1901-3. TJior Jioi'idanits, N'crrill, Frans. Conn. Acad., XI. p. 19. 



190:^. llippolvte baschalis, l.cnz, Abh. Senck. naturi". Ctcs. Frankfurt, 

 XXVli, p. 382. 



1905. Pascliocai'is paschalis, Nobili, Bull. Mus. d'Hist. nat., Paris, 



P- 39-1- 



1906. Paschocaris pasclialis, Nobili, .\nn. Sci. n.'il. Zool., Paris (9), IV', 



p. 38, pi. iii, Hg. I. 



The synonymy shown above is given with confidence. Not 

 only is it at once evident from comparison between Nobili's 

 description of Paschocaris (1906) and that of Thor, as given by 

 Miss Rathbun, that the two genera are identical, but I have 

 been able to compare American examples, received under the 

 name of Thor floridanus from the United States National Museum, 

 with specimens from vS. India which unquestionably belong to the 

 form described by Nobili as Paschocaris paschalis. 



The identity of the two forms is complete, unless it be that 

 any importance can be attributed to the slightly stouter and more 

 gibbous form of the S. Indian specimens : microscopic examina- 

 tion of the appendages fails to yieXA evidence for the recognition 

 even of a subspecies in the case of the American form. The fact 

 is one of considerable interest, for, among littoral Decapoda, it is 

 most unusual to find a species inhabiting both the Atlantic and 

 the Pacific without exhibiting any distinct structural differences.* 



It is scarcely necessary to describe the species in detail for 

 good accounts have already been given by Heller, de Man, 

 Rathbun and Nobili. 



In the examples from S. India the rostrum is bifid at the 

 apex (in one specimen trifid) and bears three or four (very rarely 

 two) teeth on its dorsal margin; one of the dorsal teeth is usually 

 situated on the carapace behind the orbital notch. In the 

 American examples the apex is bifid in four specimens, trifid in a 

 fifth, and there are four dorsal teeth. 



I Faxon (Mem. Mus. Comp. Zool. Harvard, 1895, XVII, p. 235, footnote) 

 gives a list of Decapoda which have been recorded both from the (iulf of Panama 

 and from the West Indian side of y\merica: the identity of the species of AlpJieiis 

 mentioned in this list is, as he remarks, doubtful. Excluding free-swimming forms 

 such as Pasiplia'e sivado and those having a circumpolar distribution, the only 

 littoral Decapoda Natantia that I can call to mind which inhabit both the Atlantic 

 and the Indo-pacific are Peiieiis caranwte, Sfeiiopiis liispidiis, Processa 

 canalictilata and Athaiias nitesceiis, and some of these cases require further 

 investigation. 



