200 



Dr. J. Gwyn Jeffreys on the 



[June 15, 



and some young of this remarkable Brachiopod. Byssus long, tubular, 

 and flexible, attached to a fragment of the ease of a tubular Eoraminifer. 



Shell inequivalve, triangular, imperforate, of a fibrous texture : leak 

 prominent and pointed, but not incurved : hyssal foramen elongated : 

 hinge-line narrow : skeleton composed of two funnel-shaped processes, 

 which diverge from the beak in the upper or larger valve, and of two 

 blade-like processes, besides an upright plate (like the hand or index of 

 a sundial) in the upper part of the lower or smaller valve. 



Its nearest ally is jRhyncJionella, from which it appears to be dis- 

 tinguishable only by the straight instead of incurved beak, and by the 

 arms or brachial cirri not being coiled. 



I know of one species only, which I propose to name gnomon. It has 

 been figured by Mr. Davidson in the publications of the Palseonto- 

 graphical Society for 1874, pi. i. f. 7-10. 



'Valorous' Expedition, 1100-1750 fms.; 'Porcupine' Expedition, 1869, 

 1380-1443 fms. 



G-LOMUS*, Jeifr. 



Shell nearly spherical : cartilage internal, elongated : teeth numerous, 

 minute, and set obliquely. 



Has the aspect of Pectunculus and the hinge of Leda ; but the teeth 

 are not arranged as in either of those genera. One species only is 

 known to me, which I have named nitens ; it is minute, about of an 

 inch. It occurred in Davis Strait, 1750 fms. ; also 'Porcupine' Expedi- 

 tion, 1869, on the west coast of Ireland, 1180-1476 fms., and North 

 Sea, 557 fms. 



SEGTJEjfziAt, Jeffr. 



Shell globular or conical, glossy, without epidermis, exquisitely 

 sculptured ; upper part of the last whorl deeply and widely grooved : 

 jpillar abruptly notched below, and exhibiting a small tooth-like process : 

 base either deeply umbilicated or imperforate. 



This genus evidently belongs to the Solarium family, and is allied to 

 that subgenus or section of the genus Solarium which the late Dr. J. E. 

 Grray named Philijppia, and founded on the Trochus hyhridus of Linne. 

 Seguenzia differs, however, from Solarium and from every other genus 

 of that family in the last whorl having a deep and wide groove, which 

 is placed in the upper part, instead of a narrow slit placed in the middle 

 or periphery as in Scissurella and Pleurotomaria ; nor is the mouth o£ 

 the shell entire as in those two genera. Three species are known to 

 me, viz. : — 



1. S.formosa,sp.Ji. Base imperforate. ' Valorous ' Expedition, North 

 Atlantic, 1450 fms. ' Porcupine ' Expedition, Bay of Biscay, off 



* A ball of thread. 



t Dedicated to Professor G-. Segiienza, the distinguished Palaeontologist at Messina. 



