On the Osteology o/Caturus anc? Osteorachia. 379 



roocleratelj long black hairs, tlie thorax and abdomen with 

 longer and more sparsely distributed hairs. Antennae black, 

 thick ; the scape covered with long black hairs, the flagellura 

 with a microscopic down. Head large, wider than the thorax, 

 developed behind the eyes to rather more than twice the length 

 of the eyes; the mandibles sericeous and bearing some long 

 black hairs. There is a black transverse band on the base 

 of the mesonotum, one down the centre of the median seg- 

 ment and a narrower one down each of its sides. Abdomen 

 not much longer than the thorax ; its petiole short, obliquely 

 raised from tlie bottom to the top. The ventral segments 

 clothed, like the dorsal, with pale golden pubescence. Lags 

 entirely black, sparsely clothed with longisli black hairs. 

 8. myrmiciformis belongs to the group of S. ocyroe. 



XXXV. — A Contribution to the Osteology of the Mesozoic 

 Artiioid Fishes Caturus and Osteorachis. Qj A. Smith 

 AVOODWAL'D, F.L.S. 



[Concluded from p. 29?.] 

 II. OSTEOBACSIS LeEBSI, SP. N., FROM THE OXFORD ClAY 



OF Peterborough. 



The unique specimen of Osteorachis in the Leeds Collec- 

 tion (Brit. Mus. no. P. 8388) comprises the hinder portion of 

 the skull, fragments of the jaws, opercular apparatus, and 

 pectoral arch, and part of the vertebral column, all undoubt- 

 edly belonging to one and the same individual. It is of 

 interest not only on account of its gigantic size, but also as 

 being the first known example of the genus of Upper Jurassic 

 age. As its teeth are relatively larger and stouter than those 

 of the typical species {0. macrocephalus) from the Lower 

 Lias, while their enamelled apex seems to be shorter, the 

 species it represents is evidently new, and may be named 

 0. Leedsi, in honour of its discoverer. In the anterior half 

 of the dentary in the Oxfordian fossil the length occupied by 

 the bases of three consecutive teeth at least equals, and usually 

 exceeds, the depth of the bone bearing them ; whereas in 

 0. macrocephalus the corresponding length is always less 

 than the depth of the bone. 



The following are some of the principal measurements 

 obtainable : — 



