TESCH— PTEROPODA AND HETEROPODA 



173 



1. ENUMERATION OF THE SPECIES. 

 Atlantidse. 



Oxygyrus Benson. 



1. Oxygyrus rangi (Souleyet). (Plate 12, %. 3.) 



Stat. N (1), Chagos Archipelago. 



The only specimen has been figured here in order to show the extension of the chalky 

 part of the shell with the spiral undulating lines, which part is very distinctly separated (at 

 the under side of the shell at least) from the horny part. The shell, with a maximum 

 diameter of 1^ mm. without the keel, represents a stage of growth, immediately following 

 that figured by Macdonald*. As to further particulars I may refer to my former 

 publications on this subject "f". 



Protatlanta Tesch. 



2. Protatlanta souleyeti (E. A. Smith). 



Stat, n (14), N. of N. Saya de Malha Bank. 



Contrary to my former statement! about Souleyet's specimens, I may remark that the 

 shell is quite chalky and not at all horny, as has been rightly pointed out by E. A. Smith §. 

 This difference may possibly be ascribed to the very long conservation of Souleyet's 

 specimens, though they looked cpiite well preserved. Except for this difference, I have 

 nothing to add to my former investigations. All the specimens had lost their keel, 

 which, as is well known, is very liable to be detached. 



This is the first record of this species from the Indian Ocean, all former notes 

 mentioning it as occurring in the Atlantic. 



Atlanta Lesueur. 



3. Atlanta peroni Lesueur. 



Stat. N (1), P (3), Chagos Archipelago; q (2), u (l), Farquhar ; hh (1), mm (1), 

 Amirante Group. 



4. Atlanta lesueuri Souleyet. 



Stat. L (1), E. of Chagos Archipelago; n (21), N. of N. Saya de Malha Bank ; u (1), 

 Farquhar; mm (1), Amirante Group. 



5. Atlanta injlata Souleyet. 



Stat, n (132), N. of N. Saya de Malha Bank. 



* On the anatomy and classification of the Heteropoda, Trails. Roy. Soc. Edinb. vol. xxiii. 1862. The 

 figure here referred to has been copied by me (Die Heteropoden der Siboga-Expedition, Siboya-Expedilie, 

 Monogr. li. Leiden, 1906, PI. vn. fig. 5. 



t Especially to : Systematic monograph of the Atlantidse, etc., Notes Leyden Museum, vol. xxx. pp. 6, 7. 



X I.e. p. 3. § Challenger Report, lxxii. (Heteropoda), 1888, p. 44. 



