156 SHUFELDT. 



In describing the spinal column in any mammal it has been the rule 

 of the present writer to consider all those vertebree between the skull and 

 the first one in the chain, proceeding backward, that bears a pair of true, 

 free ribs, as cervical vertebrse; all those bearing a pair of true, free ribs, 

 as dorsal or thoracic vertebras ; all those between these last and where they 

 coossify to form the "pelvic sacrum," as lumbar vertebree ; all those fusing 

 together between the ilia of the pelvis, as sacral vertebrse; and all the 

 rest to the end of the column, or chain, as caudal vertebrse. This rule 

 has been here applied to Gynoceplialus. (Figures of vertebra will be 

 found upon Plates II to V of the present memoir, that is figures 7, 8, 10, 

 11, 12, 13, 14, and 17.) 



• In describing the spinal column of the insectivore here being considered, 

 the" specimen furnished by Steere has been selected ; constant references, 

 however, will be made to the others, designating them as 2 and 3, respec- 

 tively, as already indicated. 



There is nothing especially unusual in the vertebral column of Cyno- 

 cephalus, as it is strictly mammalian in character, with all of the vertebrae 

 reduced to their simplest forms for an insectivorous animal. Even in 

 the matter of number these bones may agree with others among the 

 Insectivora, as in the case of the common European mole (Talpa europcea), 

 which has in its vertebral column 7 cervical, 13 thoracic, 6 lumbar, 5 

 sacral, and 11 caudal vertebrae, the tail simply being somewhat longer in 

 Cynocephalus. 



Viewed in its entirety in the latter it is to be noted that the atlas is 

 by far the largest vertebra in the chain; the axis is the next in size and 

 is considerably smaller, being about equal in bulk to the last lumbar. 

 The succeeding five cervical, and the first dorsal are all large vertebrffi. 

 which very gradually decrease in size as we approach the dorsal region of 

 the spine. Prom the second dorsal to the seventh inclusive the vertebrae 

 continue gradually to diminish in size ; except the terminal caudals, the 

 seventh dorsal is about the smallest one in the column ; beyond the seventh 

 dorsal the vertebra gradually increase again, become miich larger and of 

 different character in the lumbar region, and terminate with the largest 

 one of all, which articulates with the anterior vertebra of the pelvic sacrum. 

 The first lumbar bears considerable resemblance to the last dorsal, but is 

 distinguished by not supporting a pair of facets for ribs. 



The vertebrae composing the sacrum fuse very solidly, but the lines 

 of demarcation between the central and the neural spines are always more 

 or less distinguishable, more so in some specimens (1 and 3) than in 

 others (2). The first caudal vertebra, which is free, resembles the last 

 sacral, and the same may be said of the second, third, and fourth caudals, 

 although the resemblance becomes gradually less evident as we proceed 

 toward the end of the tail. This dissimilarity continues to increase rather 

 rapidly, although never abruptly, as we follow the caudal series to its 



