48 Shufeldt — Robert Collett on Pteri/combns brama Fries. 



over the 25th vertebra. The last two pairs of ribs articulate with the 

 parapophyses of the 24th vertebra. 



There are fifty vertebrse in the spinal column, of which 24 are thoracic 

 and 26 caudal. The body of the first vertebra is rudimentary, while its 

 neural spine is well developed. The ribs articulate with the third to the 

 twenty-fourth vertebra* inclusive. 



The neurapophyses (neural spines) are remarkably robust and broad, 

 especially in the thoracic region, where at their bases they have a longi- 

 tudinal diameter almost equal to the length of the body of the vertebra to 

 which any particular spine is attached. (See Plates.) 



For this reason, these neurapophyses almost come in contact with each 

 other, anteriorly and posteriorly, at their bases. As we pass backward, 

 these neural spines of the thoracic vertebra? become more slender, although 

 in this part of the spinal column the distance between them, at their 

 bases, is less than their own longitudinal diameter, in the case of any 

 two contiguous spines. In the caudal region they become more and 

 more slender as we approach the tail, though still stouter than we find 

 them in Brama. 



The first and second neural spines are vertical, or inclined slightly for- 

 ward, the remaining ones are as we usually find them. 



The most lofty ones are met with on the ultimate thoracic vertebrse 

 (37 mm. ). 



The parapophyses of all the rib-bearing vertebra? are directed down- 

 ward, and each lias a length somewhat exceeding the depth of the body 

 of the vertebra to which any particular one belongs. The parial para- 

 pophyses of any vertebra in the abdominal region fail to come in contact 

 mesially, and therefore do not form true hsemal arches. 



On the caudal vertebne the haemal spines are at once greatly produced ; 

 the one on the leading caudal vertebra possessing a length of 45 mm. 

 Their antero-posterior diameters at their bases equal those of the corre- 

 sponding neural spines in any particular vertebra, and as we proceed 

 backward the amount of reduction in point of size is also nearly propor- 

 tionately coequal. 



Secondary rHbs ("Scleral-Spina?" : supplemental or auxiliary ribs) are 

 to be found on all the anterior vertebne of the spinal column until we 

 reach the. second or third ultimate abdominal ones, where there is not 

 the slightest trace of them in the specimen at hand. 



On the first and second vertebra? they are attached to the hsemal arch; 

 on the third to the seventh they articulate with the centrum of the 

 vertebra ( " Corpus: " " Epicentralia") ; on the remaining vertebra? with 

 the anterior surface of the superior border of the rib ( " Epipleuralia "). 

 These auxiliary ribs attain their greatest length (20 nun.) in the mid- 

 series of the thoracic region, where they about equal the length of four of 

 the centra of the vertebra?. 



The interneural spines (the dorsal interspinal bones), are immense, 

 very broad, and so close together that they are in contact with each other 

 along their entire lengths, thus forming an almost continuous plate of 

 bone in the anterior region of the spinal column. 



