356 Ml*. J. S. Gaskoiii on the (jenus Pachybathron, 



lot.tirorfri', rufo 



XXXll. — On the Genus Pacliybathrou, a7id on some new Speeiiggi 

 0/ Marginella. By J. S. Gaskoin, Esq. 



[With a Plate.] 



Genus Pachybathron. 



Testa subcyliudrica, lougitudinalitcr striata, uuicolor alba opaca, 

 vel colore ornata ; posticc latior ; varice lato, crasso, plauo, ad 

 marginem exteriorcui abrujito, basin totam coluniellse, partenique 

 anteriorciu tertiam tcstse latcris efFormaute, et iatitudinc decres- 

 cendo ad dorsum canalis desinente, muuita; spira plana, plus 

 minusvc acuminata, anfractibus apparentibus ; apcrtura angus- 

 tiuscula, elongata, parum arcuata, posteriori non rostrata, den- 

 ticubs fortibus remotis trans basin sulcumque columellarcm ex- 

 tensis ; labro crasso, denticulate. 



Shell subcylindrical, longitudinally striated, opake-white or 

 with colour ; greater diameter posteriorly ; a broad, thick and 

 flat varix, abrupt at its outer edge, forms the entire base of the 

 columella and the anterior third of the side of the shell, aud di- 

 minishing in width terminates on the dorsum of the channel ; 

 spire flat, more or less acuminated, volutions perceptible ; aper- 

 ture rather narrow, slightly curved, posterior extremity conti- 

 nuous ; strong, distant denticulations extend over the base and 

 columellar groove ; lij) thick and denticulated. 



No complaint can be made that the species forming this new 

 genus have been separated from any other, as they are now for 

 the first time described. This genus possesses characters of 

 Marginella, of Cassis, and of Cyprcsa ; but difl"ers so essentially 

 from each, that I cannot associate it with any one of them. 



Pachybathron cassidiforme. 



Testa subcylindiico-ovata, opaca alba, leviter trifasciata, dorso 

 longitudinal iter rude striata; s])ira brevissima, subacuminata ; 

 anfractibus quatuor prominulis, irregulariter crenulatis, ultimi 

 raargine posteriori carinam nodulosam extus sulco profundo cir- 

 cumdatam ad finem exteriorem aperturje desinente, a]jice sub- 

 obtuso prominulo ; basi subrotundata, lata, crassissima, ad mar- 

 ginem exteriorem abrupte tei'minata, et trans partem tertiam an- 

 teriorem testae latcris ad cxtremitatem columellarem desinente ; 

 apertura angustiuseula, parura arcuata ; labro crasso, margine in- 

 tcriori cxiliter dcnticulato ; margine columellari dentes 12-14 

 lineares remotos, basin transeuntes et ad marginem intcriorem 

 sulci columellaris dcsinentes exhibente ; sulco columellari lato, 



