XIX. DESCRIPTION OF SOME SPECIMENS 



OF P LEU ROTO M A CONGENER, E. A. 



SMITH, FROM THE ANDAMAN SEA, 



WITH SPECIAL REFERENCE TO 



CERTAIN PECULIARITIES OF 



THE APERTURE. 



By E W. VrEdenburg, B.L., B.Sc, F.G.S., etc., Superinten- 

 dent, Geological Survey of India {communicated with the kind 

 permission of the Director, Geological Survey of India), 



(Plate XII). 



Pleurotoma congener, one of the most beautiful amongst the 

 Pleurotomidae of the Indian Ocean, was first described in 1894 

 by Mr. E. A. Smith from specimens in the collections obtained 

 during the cruises of H.M. Indian Marine Survey Steamer " In- 

 vestigator " from the depth of 128 fathoms in the Bay of Bengal, 

 and between 142 and 400 fathoms west of Colombo off the coast 

 of Ceylon. 



As is so frequently the case in consequence of the fragility of 

 the aperture in the Pleurotomidae, the edge of the outer lip is 

 missing in the original types described by Mr. E. A. Smith, Since 

 the publication of the original description, further specimens have 

 been obtained by the Marine Survey from the Andaman Sea (in 

 Lat. 13° 17' I5"N., Long. 93° 10' 25"E.), in depths of 185 fathoms. 

 Many of the shells are partly overgrown by organisms and were ap- 

 parently dead. at the time when they were dredged up, but in two 

 of them the aperture is practically perfect and exhibits, along the 

 outer lip, features of such a singular nature that they have been 

 thought worthy of special notice. As the specimens differ in seve- 

 ral details from the original type, it will be useful to give a com- 

 plete description. 



Pleurotoma (Gemmula) congener, E. A. Smith. 



1879. Pleurotoma covonif era, Martin, Tertiaerscliichten aiif Java, p. 6i, 



pi. xi, fig. 2. 

 1884. Pleurotoma coronifera, Martin, Saniml. des geol. R. Jlliis. in 



Leiden, ist ser., Ill, p. 58, pi. iv, fig. 58. 



1894. Pleurotoma congener, E. A. Smith, Ann. Mag. Nat. Hist. (6), xiv, 



p. 160, pi. iii, figs. 4, 5. 



1895. Pleurotoma (s. sti .) coronifera, Martin, Samml. des geol. R. Mas. 



in Leiden (new series), I, p. 38. 

 non Pleurotoma coronifera, Bellardi, Moll. terr. terz. Piem. e 

 Lig., 2d part, p. 34, fig. 20 (1877). 



