540 ME. S. HANLET ON NEW SPECIES OF DONAX. 



trails utrinque ascendens, in medio convexus, flexura nulla. Li- 

 gamentum breve. Dentes laterales nulli. 



Long. 1-5, lat. 1 poll. Hob. ? 



This unique and aberrant species reminds one of a young serra ; 

 but its contour is much more curved and elongated. Although 

 smooth to the eye, its hinder surface, under the glass, exhibits 

 faint radiating striolse towards the ventral margin. I suspect that 

 in a younger stage the marked radiating striae upon the blunt 

 umbonal ridge are nob developed. 



DoNAX LiSTEEi, n. sp. (Plate XII. fig. 2.) 



T. abbreviato-trigona, subinsequilateralis, sublaevigata, intus 

 purpurea, estus omnino albido-purpurascens, zonis saturatioribus 

 remotis ornata, antice subventricosa (seu convexa), postice sub- 

 compressa ; area postica rugis concentricis tenuibus, striisque 

 numerosis inconspicuis arctis decussatim scabra. Margo dorsalis 

 utrinque (prsesertim postice) declivis et subrectus ; margo ven- 

 tralis baud crenatus. Dentes laterales satis manifesti. 



Long. 1-15, lat. 1 poll. Rob. ? 



Thisrare shell, formerly in Belcher's collection, differs alike from, 

 yet resembles, that figure in Lister (pi. 391. fig. 230) from which, 

 and the words "extus intusquepurjjurascens," G-melin fabricated 

 his Tellina piirpicrascens, and from the Donax compressus of La- 

 marck: — from the former, which is also more equilateral, by its less 

 cuneiform hinder termination ; from the latter in being rounder 

 and much higher from the beak to its opposite edge, and by being 

 less peaked in front. I observe that the two shells are con- 

 founded in the more recent monographs, and the expressive 

 and well-defined Lamarckian species is suppressed in favour of 

 a name based upon a figure which does not even exhibit a hinge, 

 so that its very genus is problematical : if a Donax, it is more 

 like Eeeve's figure of deltoides. The hinder sculpture in our 

 unique specimen has a tendency to overlap the obtuse umbonal 

 ridge near the ventral edge. 



Donax elavidus, n. sp. (Plate XII. fig. 3.) 



T. subcordato-trigona, abbreviata, valde insequilateralis, antice 

 compressa et rotundato-acuminata, postice brevis et subventricosa; 

 extus flavescens, intus albida, baud radiata, aut maculata, nitida, 

 Isevis, sed extremitatem posticam versus transversim sulcata seu 

 plicata. Costa umbonalis nulla. Margo posticus convexus ; 

 margo ventralis postice subgibboso-arcuatus, intus subcrenulatus. 

 Dentes laterales satis manifesti. 



Long. 0-5, lat. 0*4 poll. Kab. Borneo (teste Geale.) 



