REPTILIA : LIMNOSCELIS 



35 



dilated, scapular part is curved upward in a vertical plane and 

 obliquely backward in the articulate skeleton, reaching nearly to 

 the upper end of the scapula, flattened from side to side above. 

 The cleithrum is small and vestigial, smaller than in Diadectes, 

 a slender, cylindroid bone, reaching quite to the superior anterior 

 angle of the scapula, but not expanded over the end, as in the 

 temnospondyls. It is dilated at its lower end to articulate with 

 the attenuated upper extremity of the clavicle, lying between 

 the clavicle and the front margin of the 

 scapula. It is only a little more than 

 two inches in length. The scapula is 

 very short. The blade above is narrow, 

 thinner, and curved outward on its front 

 part, thickened at its posterior superior 

 border. Its upper end is truncated, and 

 doubtless had a suprascapular, carti- 

 laginous continuation, possibly the rep- 

 resentative unossified of the upper end 

 of the cleithrum. The glenoid fossa is 

 deep and large, the stout metacoracoid 

 extending far back relatively. The pos- 

 terior border of the scapula is curved 

 nearly uniformly from the angle to the 

 extremity of the preglenoid facet, which 

 is large and flattened. There is a dis- 

 tinct supraglenoid fossa a little below 

 the middle of the bone, between the 

 borders which diverge near the middle 



of the length of the scapula; it is pierced in the usual temnospondyl 

 way for the passage of the supraglenoid canal. I have observed 

 this foramen in this position in scapulae which I refer to the genus 

 Ophiacodon, but usually in the Pelycosauria the opening pierces 

 the bone in front of the scapular margin. I had supposed that this 

 foramen was characteristic of these old orders of reptiles, never 

 having seen any reference to it in literature of other orders of verte- 

 brates. But I am surprised to find that it is quite typical of cer- 

 tain lizards, and it perhaps occurs in other reptiles. In the present 



Fig. io. — Limnoscelis pa- 

 ludis. Left clavicle and cleith- 

 rum from in front, two-fifths 

 natural size. 



