OSTEOLOCY. 37 



At the sixth caiuhxl the broad diapophysis is divided into an anterior and a 

 posterior ]X)rtion, the hitter of wliieh becomes obsolete at the 15th, and the 

 former at about tiie 18th vertel:)ra. In Gynniura the diapophyses are much less 

 developed, having an anterior but not a posterior origin on each vertebra, while 

 the prezygapophyses, in the sjwcimen examined, end with the third caudal. 



The chevron bont-s are largely developed, and as in Gymnura occur in con- 

 nection with all but the few terminal vertebrae. In Gymnura, however, the 

 two lateral elements of each chevron are unfused except in case of the sec(jnd 

 and third which are united at their origin medially. Their antero-posterior 

 extent is much greater in Gymnui'a. In Solenodon the two lateral elements of 

 the first chevi'on are thin terete sj^icules of bone, approximated distally but 

 separate. The second chevron is similar but the two elements are fused both 

 proximally and distally forming a closed canal for the caudal artery. The same 

 condition prevails in the two following, whose distal parts are in addition ex- 

 panded laterally. In all the succeeding chevron bones the arterial canal is 

 o]>en ventrally. The last chevron is Ijetween the 21st and the 22il caudals. 

 In Solenodon ciibiuius Peters has figured but twenty chevron bones. There are 

 21 in S. paradoxus. 



The ribs and sternum (Plate 7, figs. 11, 12) of Solenodon are remarkably 

 strong and well ossified. The sternal portions of the first twelve ribs are bony, 

 while the thirteenth is cartilaginous at the distal end only. The two succeeding 

 ribs are connected by a cartilaginous strand to the ventral margin of the other 

 sternal ribs, while the 16th rili is short and without such connection. The 

 sternal portion of the first rib is broad at its articulation with the manubrium 

 along the posterior curve of its antero-lateral expansion. The sternal portions 

 of the three I'ibs following articulate each at the jioint of union of the first and 

 second, second antl third, and third and fourth sternal elements respectively 

 The fifth rib is inserted at the junction of the fourth and fifth sternal elements, 

 and its sternal portion is of two separately ossified pieces. The fifth sternal 

 element serves for the attachment, directly or secondarily of ribs 6 to 14 both 

 inclusive. The sixth and seventh ribs are inserted separately, one directly in 

 front of the other; the latter has three bony i)ortions ventral to the main dorsal 

 shaft. The sternal portions of rijjs 8,9,10, and 1 1 , have each a proximal section 

 aI)out 13 mm. l()ng, making nearly a right angle with the more distal portion 

 running antero-internally to the sternum and forming the ventral rim of the 

 thoracic basket. These more distal pieces of these ribs just mentioned, are fused 

 into a single bony mass, on whose ectal surface may be traced the lines of union, 



