G. H. Wieland — Archelon ischyros. 403 



The dorsal vertebroe, ten in number, have not as jet been 

 completely examined. They present, inferiorly, a striking 

 resemblance to those of Protosphargis as restored by Capel- 

 lini, but with this important exception : in Protosjphargis the 

 third dorsal vertebra is the largest, in Archelon the sixth is by 

 far the largest.* They have nearly, or wholly, flat ends. The 

 neural arches are evidently rather flat bodies, articulating with 

 the centra and forming the heavy dorsal ridge mentioned 

 before. They have little or no connection with the carapace. 

 The dorsal centra increase in size to the sixth. The seventh, 

 eighth and ninth rapidly diminish to the sacral, which are 

 short and flat, and three in number. Following the sacral 

 were five or more caudal vertehrce with articulating neural 

 arches, and then fully ten whose arches, like those of the cervical 

 vertebrae of Protosphargis and unlike the caudal vertebrae of 

 Sphargis^ were homologous parts of the centra.f Presumably 

 these were situated beyond the pygal. Of these caudal verte- 

 brae, ten or more were recovered, wholly or in part. 



Coracoid. — The coracoid is a shapely and comparatively slen- 

 der bone, 77^™ in length. The lateral surface is finely striate, 

 with larger parallel striations distally. The articulating sur- 

 face is very distinctly tuberculated, some of the tuberculations 

 being somewhat rounded, others quite conical and so much as 

 1''" across at base and 1*5°" high. 



The articular face is strongly convex anteroposteriorly, and 

 a little less so laterally, but in such manner that near the outer 

 edge of the surface for the procoracoscapula there is a slight 

 concavity, while the humeral surface is broadly flat and looked 

 well downward and forward. For the first two-fifths of its 

 length the shaft is in section isosceles right triangular, with 

 the right angle on the inner side. The upper inner side of the 

 shaft, however, takes a long turn to the outer face just beyond 

 the middle, leaving the distal end comparatively thin and flat. 

 The coracoid is much larger than in Protostega, as are all the 

 bones, but bears strong resemblances. 



Measuremertts of Coracoid. 



Meters. 



Greatest length -77 



Greatest distal width . _ _ * 1 42 



Least circumference of shaft '25 



Greatest length of articular face _ '20 



Greatest breadth of articular face '145 



* n Chelonio Veronese, Eeale Accad. dei Linci, 1883-4 (Rome). 



f See the beautiful memoir, — Osieologie du Spliargis Luth. (Sphargis coriacea) 

 par M. Paul Gervais, pp. 199-227 Planche Y, — YIII. Nouvelles Archives du 

 Museum, Tome 8, 1872 (Paris). 



