I.;:, 



This species is known from the smooth forma ofC tun idum by 

 the greater proportionate length, less thickening of the month, anil 

 the very conspicuous mncro on the otherwise Battened ping. As 



Crag sliells are prone to variation, it is probably DOl a mark of Bpe- 



rific difference that the mucro varies in shape, being sometimes 

 straight, sometimes heut as in the figure, sometimes long, sometimes 

 short, sometimes swollen so as to approach 0. trachea, I' is pro- 

 bably one of these specimens that is figured at ."> a* 



Genus Brochina, (iray. 



Testa Gteeo similie, lands; apertura simplici, acuta; septa ma- 

 tnillato. Operculum convexum ; anfractibus linea elevata in- 

 structis. 



It will he a remarkahle coincidence, should it hereafter appear 

 that all the shells with mamillated plug and sharp mouth have the 

 convex operculum. At present we can only distinguish Brochina 

 from Cceeum by the latter character. As the same terraced Btrnc- 

 ture appears in the concave forms, as some of these are almost flat, 

 and as the amount of convexity differs in different individuals, or in 

 the same individual according to accidents in drying, this alone tonus 

 a scarcely sufficient generic character. 



Brochina, Gray, Guide Moll. p. 101. — Cceeum, pars, auct. 



37. Brochina glabra, Mont, (diagn. auct.) 



Br. t. parva, tereti, Icevi, tenui, subdiaphana ; apertura haud 

 contractu, haud declivi, haud tumida ; scj)to tnamillato, plus 

 minttsve elevato, apice nullo ; margine laterali circulari; mar- 

 ginibus decollatis, haud eonspicuis. Test. jun. planorbifbrmi, 

 anfr. ii. et dimidio, tumidis, tenuissimis. Opcrculo pellucido, 

 comeo, extante ; plerumque medio planato, hemogeneoi <l<n> 

 eonxco, lateribus j)lus minusve dwergentibus, tinea spirals eat- 

 tante, anfr. v.-vii. ; interdum omnino <-i>ii'-t> go, tinea spirali 

 apicem versus ascendente. 



Test, jun. spir. diam. 'Oil. 



Test. jun. elongata, long. - 03, lat. *006. 



Test, adolesc. long. '055, lat. '008— '012. 



Test, adult, long. -008, lat. -012— -01 ">. 



llatj. British Seas (vide Forbes fy Hanley) \ Mediterranean 

 (If Andrew} ; Piedmont {Jeffreys) ; Cephalonia (Bean)i fossil in 

 Cor. Crag (8. Wood). 



\-=.T)entalium minutum, Linn, ed. \ii. p. 1264 . Dillw. Rec. Shells, 

 vol. ii. p. 10o'8 (vide antra, p. 1). 



Dentalium glabrum, Mont. Test. Br. vol. ii. p. 197(1803 M 



• Students have cause to regret that t lu- invaluable leriea of Cn 

 bvm which the monograph was compiled were not aamed bj the anthoi ; 

 he so generously presented them t<> the British Hntfflim In the absence of a 

 eopy of the work in the Zoological Department, they are still nanamed, ■< 

 fication of types is retarded. 



