E. ETHERLDGE ON A TERTIARY HEMIPATAGTTS. 445 



by Dr. Laube, in two instances exhibiting points of structure ap- 

 parently not shown in his specimens. 



Genus Hemipatagus, Desor. 

 Hemipatagus Woodsii, sp. nov. Plate XXI. figs. 1-7. 



Sp. char. Cordiform, a little quadrangular ; anterior end sulcated, 

 rounded, or inclined to be a little truncate ; posterior end truncate 

 and considerably overhanging • sides sloping gently from the apical 

 region. The test is highest immediately posterior to the apical 

 disk, whence the summit is somewhat flattened to the edge of the 

 nearly vertical anterior end. The ambulacra are broadly lanceolate, 

 with blunt or abrupt apices ; the anterior pair are widely divergent, 

 and longer than the posterior, with their points somewhat curved 

 outwards. The odd ambulacrum is placed in a deep groove, and 

 only represented by minute equidistant round pores, which are lost 

 befdre reaching the mouth ; the sides of the groove in which the 

 odd ambulacrum is placed are densely but minutely tuberculated. 

 The ambulacra! pores are deeply sunk, conjugate, and obliquely 

 divergent ; in the posterior pair of ambulacra there are from eight 

 to ten pairs of pores in each series ; the anterior series of pores of 

 the anterior pair of ambulacra extend scarcely halfway from the 

 apices of the ambulacra towards the apical disk ; in each of the 

 posterior series of the same ambulacra there are from eleven to 

 thirteen pairs of pores. The whole of the interambulacral areas are 

 densely and minutely tuberculated ; the primary tubercles are large 

 and few, and confined to the anterior pair, and to the extreme an- 

 terior portion of the lateral pair of interambulacra, and are sur- 

 rounded by a deep scrobicula ; the odd interambulacrum forms a 

 somewhat ©btuse angle. The apical disk is a little excentric, some- 

 what nearer the posterior end ; the genital pores (h, fig. 5) are four 

 in number, the posterior pair being wider apart than the anterior ; 

 the result of the intervention of a pyriform plate, which bears the 

 madreporiform body (a, fig. 5). The anal orifice is oval, and situated 

 in the concave and truncated posterior end (see fig. 4), which is bent 

 inwards from below, giving to the termination of the odd interam- 

 bulacrum a very overhanging or beak-like appearance (fig. 3). Below 

 the anal orifice is a spectacle-shaped fasciole, carrying on each side 

 a circlet of perforated primary tubercles, considerably smaller than 

 those on the interambulacra ; the anal plates are not preserved. The 

 ventral or oral surface (fig. 2) is concave and divisible into three well- 

 marked portions, two corresponding lateral parts strongly tubercu- 

 lated, and a central portion comparatively smooth, in which is placed 

 the mouth, and called by Prof. Duncan and Dr. Laube, in their de- 

 scriptions of H. Forhesii, the " plastron." The tubercles of the lateral 

 portions of the ventral surface are primary and perforated, nearly 

 intermediate in size between those of the interambulacra and the sub- 

 anal fasciole, but with one edge, that towards the anterior end, con- 

 stantly in contact with the scrobicular circle (fig. 7). The "plastron" 

 is narrowed anteriorly, but widens out posteriorly, where it is 



