VIII. ON A NEW SPECIES OF THALASSEM A 



FROM THE GULF OF MANAAR WITH 



NOTES ON THURSTON'S SPECIES 



T. FORM U LOSU M. 



By B. Prashad, D.Sc, Offg. Director of Fisheries, 

 Bengal, Bihar and Orissa, Calcutta. 



Thurston in his account of the Fauna of the Gulf of Manaar • 

 records the occurrence of a species of the genus Thalassema, 

 Lamarck,* as the only representative of the Gephyrea Chaetifera 

 in this region. Regarding the exact locality from which the 

 specimens were obtained, he adds the following note — ''Of the 

 four species dredged oH Rameshwaram Island, only Dendrostoma 

 signifer was abundant," 



On the authority of Dr. Selenka, who identified the collection 

 of Gephyrea, the name of the species in the Bulletin is given as 

 Thalassema formulosum. Curiously enough, though the authorities 

 for the other names are cited in all cases, the name of the author 

 of T. formulosum is omitted. Selenka, so far as I have been 

 able to ascertain, did not describe any species as T. formulosum, 

 nor has any other author described one of this name. Probably 

 the species was T. formosulum, Lampert,* and the name in 

 Thurston's work is only a lapsus calami, or Selenka meant to 

 describe a new species under this name, though he never did so. 

 In his revision of the genus Thalassema,^ Shipley does not make 

 any reference to Thurston's record and was probably not acquaint- 

 ed with it. According to him T. formosulum had been obtained 

 from Cavitte near Manila and Shanghai. Sluiter^ has since re- 

 corded the same species from Labuan Tring and Sapeh-Bai, Sum- 

 bawa, from the material collected by the Siboga Expedition in the 

 Dutch East Indies. If my interpretation regarding the name of 

 the species recorded by Thurston is correct, then the species T. 

 formosulum has a very wide range of distribution in the Pacific 

 and the Indian Ocean. No specimens of the genus Thalassema 

 were obtained during Herdman's investigations * of the Fauna of 



i Bull. Madras Mus., Ill, p. ii6 (1895). 



2 In my previous papers I followed Annandale and Kemp {Mem. Ind. Mus., 

 V, p. 58 and Rec. Iiid. Mus. XVI, pp. 399-402) in assigning the authorship of 

 Thalassema to Gaertner ; this, however, as Shipley had pointed out, was not quite 

 correct, as the real author is Lamarck. 



3 Zeitschr. Wiss. ZooL, XXXIX, p. 339 (1883). 



* Willey's Zool. Results, p. 348 (Cambridge, 1889). 



^ Siboga-Expeditie, XXV, p. 48 (1902). 



^ Rept. Ceylon Pearl Fisheries and Marine Biology, pt. I, p. 169 (1903). 



