168 THE VOYAGE OF H.M.S, CHALLENGER. 



Length 3f mm., height S^, diameter 2^. 



Habitat. — Station 185b, east of Cape York, North AustraUa, at a depth of 155 

 fathoms ; coral sand. 



This species differs from Verticordia multicostata, A. Adams, in form and the much 

 less pronounced lirse. 



Verticordia ivoodii, n. sp. (PI. XXV. figs. 7-7&). 



Testa ventricosa, insequilateralis, tenuis, irregulariter obtusatim cordata, sordide albida, 

 epidermide dilute fuscescente subarenacea induta, radiatim inconspicue lirata, seque longa 

 ac alta, intus margaritacea, obsolete radiatim substriata. Margo dorsi anticus brevis, 

 prope umbones leviter excavatus, parum obliquus, posticus longior, paulo arcuatus, 

 subhorizontalis. Margo ventralis dorsali multo angustior, rotundatus, lateribus vix 

 convexis junctus. Umbones magni, prominentes, antice incurvati, baud acuti, aliquanto 

 ante medium collocati. Lunula parva, depressa, cordiformis. Dens cardinalis valvse 

 dextrse prominens, tuberculiformis, mediocriter magnus. Ligamentum lineare, 

 marginale, partimque internum. Cicatrix anterior profunda, postica et linea pallii 

 indistinctee. 



This shell is about as long as high, very thin, rather ventricose and inequilateral. 

 It is obliquely obtusely subcordate, dirty white, and clothed with a most remarkable 

 pseudo-epidermis, which to the naked eye has a pale brown granular or sandy appearance. 

 Under the microscope the surface is seen to be covered with small granules, arranged 

 pretty regularly in numerous close-set radiating series, and being transparent, when held 

 up to the light, giving to the valves a punctate appearance as if pricked -^-ith a needle. 

 On washing the surface with very weak dilute acid the granules quickly dissolve, leaving 

 the surface punctate all over, for each granule apjaears to rest in a minute circular pit. 

 In addition to this peculiar sculpturing the surface is marked with about thirty radiating 

 rusty red elevated lines. The outline is broad above, roundly shouldered, and narrows 

 towards the lower margin. The dorsal line is a little oblique in front, short, and a trifle 

 concave ; posteriorly it is longer, faintly arcuate, and nearly horizontal. The ventral 

 margin is rounded, and curves sharply into the somewhat straight sides, of which the 

 hinder is less jierpendicular than the anterior. The umbones are rather large, prominent, 

 weU-curved over towards the front, not quite approximated, nor acute. The lunule is heart- 

 shaped, a little depressed, not circumscribed, and unequally proportioned in the two 

 valves, two-thirds of it being in the right. The hinge is composed of a single conspicuous, 

 tubercular, pearly tooth in the right valve, situated below the margin, and separated 

 from it by a groove, which receives a marginal sub-tooth or thickening in the left valve. 



