296 ME. K. S. COBBOLD ON TKILOBITES 1^-Ug. 19* x j 



raised at the edge and situated about midway in the length of the 

 shield. 



Ocular ridge. — Distinct in the interior [366], fig. 21, but 

 hardly visible in the other specimens. 



Postero-lateral border. — Furrow narrow and strongly 

 marked ; fold convex and also narrow ; the whole border, as seen 

 from behind, curves evenly down without geniculation to the lateral 

 angles, which extend farther out than the eye-lobes. 



Front. — Consisting of the convex space which connects the 

 fixed cheeks and a convex marginal rim, separated by a deep, 

 distinct, and narrow furrow. When viewed from in front, the 

 marginal rim is very much arched upwards in the middle. 



Facial suture. — Anterior branch, a little uncertain, apparently 

 convergent forwards from the eyes ; posterior branch divergent 

 backwards. 



Test : Imperfectly preserved. 



Locality and horizon. — The upper section on the Shoot- 

 Bough Road, Comley ; from the ochreous band, about 4 feet below 

 the top of the Shoot-Ron gh-Road Flags. 



Faunal Grouping of the Trilobites. 



The trilobites of the Comley Sandstone fall naturally into three 

 principal groups or faunas — an upper with Parade xides davidis, a 

 median with P. groomii, and a lower w r ith Protolenus and Callavia. 



When the fossils are collected carefully bed by bed, several minor 

 groups make their appearance, which, so far as can be judged from 

 my collection, are very distinct. The horizontal extent of the beds 

 available for examination is, however, so limited, that it is quite 

 possible that these differences may prove to be more apparent than 

 real. 



The Faunal Groups of the Comley Sandstone in Descending 

 Order of Occurrence. 



Davidis Fauna. — Shoot-Rough-Hoad Flags. 



Ptychoparia (Liostracus) pulchella, 



sp. nov. 



Ptychoparia (Liostracus) sp. indet. 



Ptychoparia (Liostracus) ? dubia, sp. 



Paradoxides davidis Salter. 

 Agnostus fallax Linnarsson. 

 Agraidos ' holocephahis Matthew. 

 Agraulos sp., ct*. Arionellus quadran 



gularis "Whitfield. 

 Microdiscus sp.,cf. M.jmnctatus Salt 



Brachiopoda (identified by Dr. Matley) :— 



Acrotreta aff. A. socialis von Seebacb. 

 BillingseUa Undstrcemi Linnarsson, 



var. salopiensis, nov. 

 BUlingsella cobboldi, sp. nor. 



Lingidella cf. L. ferruginea Salter. 

 Lingidella (?) sp. indet. [1033]. 

 UnguleUa (?) sp. indet. [709-710]. 

 Acrothele ct*. A. gramdata Linnarsson 

 Acrotreta(Linvarssonia)sagittalisS&lt. I Orthis (?) sp 



