156 Mr. J. W. Salter on new Fossil Crustacea 



species which shows so strange a tendency to invert the position 

 of the abdomen. (See figures 1, 2.) 



Locality. Black flags (Upper and Lower Ludlow) at Lesma- 

 hago, Lanark. Found by Mr. R. Slimon of that town. 



2. C. stygius, n. sp. 



C. 8-9-uncialis, tenuissime striatus, oblongus, margine ventrali plus 

 minusve angulato. Annuli numerosi, sex ultimi solum liberi, 

 reliqui a cephalothorace tecti. Segmenta libera quam longa bis 

 latiora, ultimum precedens plus dirnidio longius. Appendices 

 caudales validae, centralis longa subrecta costata, laterales latse. 



This of all the species is the most common, and may literally 

 be said to form mountains in Lanarkshire. Large tracts of 

 moorland at and around Nutberry Hill and on the Logan Water 

 and Nethan Water, S.AV. of Lanark, are composed of blackish 

 slate, with many stone bands amongst it ; and of these shales 

 nearly every slab has some fragment or other of a Ceratiocaris, 

 and often they are perfect. Mr. Slimon of Lesmahago has col- 

 lected them by hundreds, and supplied many museums with 

 them*. 



The much greater proportional length of the body-segments, 

 which are not concealed beneath the carapace, will at a glance 

 distinguish the present species from C. papilio, to which species 

 its finely striated carapace and the nearly equal length of the 

 appendages closely ally it. It is possible that these two forms 

 may represent different sexes of the same species ; but there are 

 at least two varieties of carapace in C. stygius itself, one more 

 square and obtuse than the other ; and as there are also differ- 

 ences of proportion in the abdominal segments of these varieties, 

 it will be more reasonable to refer such slight differences to sex, 

 and allow the C. papilio to rank as a species. 



Locality. Lesrnahago Hills; Nutberry Hill, as above; in 

 Upper and Lower Ludlow rock. 



3. C. inornatus, M'Coy. 

 (Synopsis Foss. Woodw. Mus. pi. 1 E. fig. 4.) 



C. modicus ; cephalothorax biuncialis, quam latus bis longior, ovato- 

 oblongus, convexus, margine ventrali valde arcuato. Mucro an- 

 ticus rectus. Superficies lineis remotiusculis interruptis. Telson 

 costatum. 



On this species Prof. M'Coy founded the genus. 

 Its carapace has much the general shape of that of C. stygius, 

 but appears to have been far more convex, and has a straight, 



* I beg to call attention to Mr. Slimon's beautiful collections of the large 

 and perfect Crustacea (Pteryyoti, &c.) from these beds, and to recommend 

 him to the notice of all collectors of Silurian fossils. 



