42 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [Jan. 20, 



none, except as regards a slight depression at the base. L. 0'06, 

 B. 0-05. 



•Porcupine' Exp. 1870: Atl. St. 36. A single and not quite 

 perfect specimen. 



It is not the young of any known species of Fossarus. 



Since the above description was written I have ascertained, by 

 comparison of specimens, that this species is the Coralline-Crag 

 fossil, described and figured by the late Mr. Searles Wood under the 

 name of Lacuna reticulata — which must therefore replace the spe- 

 cific name inter junctus, which I had imposed upon this form. 



A. Not umbilicate. 



1. Seguenzia FORMOSA, Jeffreys. 



S.formosa, Jeffr. in Proc. R. S. 1876, pp. 200, 201 (woodcuts) ; 

 Ann. & Mag. Nat. Hist. 1877, p. 319 ; Journ. Linn. Soc, Zool. 

 vol. xiv. p. 605. 



'Porcupine' Exp. 1870 : Atl. St. 17«, off C. Espichel, 22. 



Distribution. ' Valorous ' Exp., off Culebra I. and Bermudas 

 (' Challenger' Exp.), G. Mexico {Pour tales), off Marocco and C. 

 Verd I. ('Talisman' Exp.), New-England coast {Verrill) ; 325- 

 2033 fms. 



Fossil. ?Miocene : Calabria {Seguema). Pliocene : Sicily {Se- 

 guenza), Bologna {Cajielliniy. 



Trocliocochlea monocingulata, Segnenza, MS. 



The sinus or slit in the outer lip of this remarkable shell would 

 seem to indicate some corresponding organization of the animal. 

 Similar instances occur in the cases of Scissurella, Emarginula, 

 Siliquaria, Pleurotomaria, and the Pleurotoma family. Professor 

 Verrill proposed to make Seguenzia the type of a distinct family ; 

 but until the animal is completely known (and not merely through 

 the operculum and odontophore), I think it would be better to 

 defer guessing as to the position of this genus in any scheme of 

 classification. 



B. Umbilicate. 



2. Seguenzia elegans\ Jeffreys. (Plate V. figs. 1, la.) 

 S. elegans, Jeffr. in Proc. R. S. 1876, p. 200. 



Shell globose, and forming a short cone, rather thin, semitrans- 

 parent, somewhat nacreous and glossy : sculpture, sharp spiral 

 ridges or keels, of which there are 4 or 5 on the body-whorl, 2 on 

 the penultimate and next whorls, and 1 on each of the upper 

 whorls ; there are also occasional and nearly microscopic thread- 

 like spiral striae between the ridges ; the interstices of the ridges, 

 and sometimes the ridges themselves, are crossed by rows of minute 

 and numerous striae in the opposite direction to the line of growth, 

 some of these striaR being curved, others oblique, straight, or alter- 

 nately arranged ; in those specimens where the cross striae extend 



' Elegant. 



