106 H. Woodward — New Phyllopodous Crustaceans. 



3. Ceratiocaris trimcatus, H. Woodw,, Plate III., Fig. 2 (nat. size). 

 The second and smaller form (Plate III., Fig. 2) measures fourteen 



lines in length and seven lines in depth ; the dorsal line is straight ; 

 the anterior end is truncated at its extremity, and the ventral 

 margin is strongly curved and terminates in an obliquely-truncated 

 posterior border (not well shown in the figure, which conveys the 

 idea of a broken edge). No eye-spot or ornamentation has been 

 observed in this species. The valves are tumid, particularly at the 

 anterior end. I propose to name this species Ceratiocaris truncatus. 



4. Dithyrocaris tenuistriatus, M'Coy, PL III., Fig. 4 (nat. size). 

 Some time since the British Museum acquired from Mr. J. H. 



Burrow, formerly of Settle, Yorkshire, a small series of Carboniferous 

 limestone fossils, among which is the valve of DitJiyrocaris, figured 

 on Plate III., Fig. 4, of the natural size. 



It agrees closely if it is not identical with the Dithyrocaris tenui- 

 striatus of M'Coy (see Synopsis Carboniferous Fossils of Ireland. 

 Dublin, 1844, 4to. p, 164, pi. 23, fig. 3), but it is one third larger. 

 It is probably also the same as Prof, de Koninck's Avicula paradoxides 

 (see De Koninck's Description des Animaux Fossiles, etc. Liege, 

 1842, 4to., pi. vi., fig. 6, p. 139). 



The valve measures 1 inch and 5 lines in length, and half an 

 inch in breadth ; it is broadest at the anterior end, contracting slightly 

 towards the posterior border, which appears to terminate in an 

 obtuse central point. The border of the carapace, for a breadth of 

 three lines, is separated from the median portion by a strongly-raised 

 keel, which follows the contour of the margin, dying out at the in- 

 terior and posterior ends of the valve. Near the anterior end, this 

 keel intersects the eye, which forms a raised narrow ridge one line 

 in length, nearly parallel with tlie mesial line, and about 2 lines 

 distant from it. Another less prominent ridge runs nearly parallel 

 with the mesial line occupying a space intermediate between it and 

 the cheek-border, but nearer the former. 



When examined with a high power, in a good light, the surface, 

 especially the border, is seen to be covered with very fine wavy strise. 



It is exceedingly dilBScult to decide whether this form had its valves 

 expanded widely, as in the recent Apus, and probably in the fossil 

 Dithyrocaris Scoideri ; or whether, as in Nebalia and Ceratiocaris, 

 they were folded down upon the sides of the animal's body. The 

 distinction seems an important one, but the frequent occurrence of 

 the united expanded valves of Ceratiocaris in the Uj)per Silurian 

 Shales of Lesmahagow, often renders it difficult to decide as to the 

 actual and normal degree of expansion or folding down of the lateral 

 borders of these crustacean shields during the lifetime of the animal. 



5. Dithyrocaris Belli, H. Woodw., Plate III., Fig. 5 (nat. size) . 

 Amongst a series of Crustacean remains, from the collection of 



Prof. Bell, of Canada, obtained in the Middle Devonian of Gaspe, 

 and left with me for examination by the kindness of Principal 

 Dawson, F.E.S., of McGill's College, Montreal, is the portion of 



