CAMPYLOSTOMA. 23 



Family— CALAPPAD^E. 



Genus — Campylostoma, Bell. 



Species unica. Campylostoma matutiforme, mild. Plate III, figs. 8 — 10. 



Descr. Carapace somewhat broader than it is long ; the surface uniformly and finely 

 granulated ; the front with two teeth, the upper margin of the orbit with three, the inner 

 one placed just above the frontal, a rather deep notch between this and the second, 

 the third or external-angular rather small, forming the first of the five latero-anterior 

 series ; the second, third, and fourth of these are triangular, of nearly equal size, and with 

 equal interspaces ; the fifth much longer than the others, and probably produced into 

 a long spine, the extremity of which is broken off in all the specimens examined.* 

 The latero-posterior margin oblique, very slightly curved ; the posterior margin a little 

 hollowed at the middle; the regions of the carapace are rather indistinct; there are 

 twelve tubercles on the surface, many of which become obsolete by age ; of these there are 

 five in a straight line across the anterior part of the carapace, au niveau with the third 

 latero-anterior tooth ; a large one on the nasogastric lobe, a smaller one on each side 

 of it on the metagastric, a small one on the urogastric, the largest of all on the 

 epicardiac, and a small one on the metacardiac : there is also a distinct one just within 

 the latero-posterior margin on the metabranchial ; a rounded, longitudinal ridge on each 

 side, extends nearly the whole length of the carapace, and a groove lies between these 

 and the central ridge on which the median tubercles are placed. The orbits are rather 

 long, and somewhat open upwards; the pterygostomian process is broad, irregularly 

 granulated, and has a broad, prominent ridge within the outer margin, and an inner 

 parallel ridge with an intervening sulcus ; the footjaAvs are wholly wanting in all the 

 specimens I have seen excepting one, and in this only the second joint of the inner footstalk 

 remains ; this is elongate, linear, and straight ; the buccal opening is narrowed forwards in 

 a curved line, each side forming the segment of a circle ; thus the opening is not triangular 

 and pointed as in those forms to which this species appears to be most nearly allied. 



Length of carapace, 1*3 inch; breadth, 1*7 inch. 



Obs. All the parts, excepting those above described, are destroyed in all the 

 specimens which I have had an opportunity of observing ; and, from this circumstance, 

 I have found considerable difficulty in coming to any satisfactory conclusion respecting the 

 affinities of this species, and the defective state of the specimens has also prevented 



* In one individual, of which I have given a figure, this part is evidently unnaturally developed. 

 See Plate III, fig. 9. 



