76 Description of Genera and Species. 



Several fragments of the form occur in the collection, all from the same locality, but fig. 

 15 represents in natural size the least incomplete specimen, though some of the fragments 

 show that members of the species must have attained a still larger size. 



Locality, — Glencartholm, Langholm, Dumfriesshire. 



Horizon. — Calciferous Sandstone Series. 



Collector. — A. Macconochie. 



Crangopsis couttsi sp. nov. PI. XII., figs. 1-7. 



Specific Characters. — Moderately large shrimp-like forms, 30-50 mm. Carapace 

 more than one- third of length of body, deeply emarginate behind, and with rounded 

 lappets edged with double marginal band, produced slightly in front into a short and 

 broad triangular keeled rostral protuberance marked off" by a depression bridged by the 

 keel, which extends back over part of the gastric region ; only faint trace of a cervical 

 fold. Antennular peduncle long and massive. Epimera of tail segments blunth' pointed 

 and directed slightly backwards ; those of second segment do not overlap forwards on 

 to those of the first. Telsoii nearly as long as the uropods, and embossed with two 

 heart-shaped keeled areas, one on each side of the median depression. 



General Description. — This is a moderately stout, shrimp-like form, with laterally 

 compressed body so that it fossilises sideways, and its thin integuments are generally 

 much wrinkled. 



The trunk, which makes up more than one-third of the body length, is evidently 

 constructed much on the lines of the previously-described species, though somewhat 

 shorter and stouter in its proportions. The carapace is of the usual form, and seen side- 

 ways it is almost rhomboidal, being a little deeper behind than in front. It has rounded 

 posterior angles, and is moderately deeply cut out along the back, leaving bare the last 

 trunk segment in the mid-line. It is edged along the sides and behind by a double 

 thickened band. In front, it is produced into a wide triangular protuberance in place 

 of a rostrum, and has wide and short orbital and antennal spines. The rostral triangle 

 is surmounted by a distinct central keel, which, extending back and bridging a depression, 

 is carried for a short distance on to the jrastric region of the carapace, where it dies down. 

 The tail is of the usual fusiform shape and somewhat stoutly built. It attains its greatest 

 depth about the second or third segment, and the segments increase in length while 

 they decrease in depth successively backwards, the sixth segment being the longest, 

 narrowest, and shallowest. All are supplied with epimera, which are deep and dn-ected 

 downwards and backwards and terminate in' rounded narrow points. The epimera of 



