320 Dr. Gwyn Jeffreys on 



mouth large, indented by the spiral ribs : outer Up tliin, pro- 

 minent, and deeply scalloped : inner Up thick, folded back on 

 the pillar, which is short and incurved ; at the bottom of the 

 pillar is a small but sharp tooth-like projection, below which 

 is a short and abrupt notch, like that of Cerithium : the groove 

 or slit on the upper part of the last whorl, and opening from 

 the mouth (which characterizes the genus), is wide and deep, 

 terminating in a curved indentation : base somewhat concave, 

 but imperforate or without any umbilicus : operculum none. 

 L. 0-2. B. 0-15. 



Station 12, 1450 fms. ; 16, 1785 fms. (fragment). 'Por- 

 cupine ' Expedition, 1870, off the coasts of Portugal, 718- 

 795 fms. 'Challenger' Expedition, Station 56, S.W. of 

 Bermudas, 1075 fms. ! Gulf of Mexico, 325 fms. (Pourtales) ! 

 Fossil in the Pliocene formation at Trapani in Sicily as S. 

 monocingulata (Seguenza, MS.). 



The peculiar and exquisite sculpture is not unlike that of 

 Adeorhis suhcarinatus. My only specimen which contained 

 the animal was in vain sacrificed at the altar of science in the 

 hope of detecting an operculum. 



Seguenzia carinata *, Jeffr. 

 Segmnzia carinata, Proc. Roy. Soc. vol. xxv. no. 173, p. 201. 



Shell forming a depressed cone, thin, transparent, glossy, 

 but not nacreous : sculpture, a sharp keel round the periphery, 

 a thread-like spiral rib below the suture of each whorl (vary- 

 ing in position), numerous but slight flexuous strias below the 

 rib, and in some specimens minute close-set curved longitu- 

 dinal stria3 on the upper whorls ; the base is smooth, or marked 

 only with microscopic lines of growth : colour glassy : suture 

 rather deep : spire short : whorls 7, compressed, slightly 

 shouldered by the infrasutural rib ; the last whorl is dispro- 

 portionally large, and the first is globular: mouth narrow, 

 rhomboidal, angulated in the middle by the keel, and below 

 by the base of the pillar : outer Up thin : inner lip filmy, 

 spread on the base: ^;t7Zar very short and incurved; it is 

 furnished near the bottom with a small tooth-like process, 

 below which is a short notch : groove broad, apparently not 

 deep ; it occupies the middle of the body-whorl between the 

 suture and the peripheral keel : umhiUcus narrow but deep, 

 exposing all the whorls, encircled and defined by a slight rib. 

 L. 0-125. B. 0-175. 



Station 13, 690 fms. ' Porcupine ' Expedition, 1870, Bay 



* Provided with a keel. 



