Bliss.] 4 [June 15, 



In the Cyprinoids the three anterior centrums are soldered to- 

 gether. The parapophyses arising from them exhibit a modification 

 of structure quite remarkable. The coalesced neural spines are 

 much developed, but the interneurals are small, and exhibit no 

 striking peculiarities. 



But it is in the Siluroid and its allied family, the Dor adidse, that this 

 enlargement of the centrums, and the modification of their apophy- 

 ses and spines is carried to its greatest extent. In these groups the 

 centrums are so firmly united that the sutures are almost obliterated. 

 The neural and interneural spines are often so thoroughly united as 

 to form a solid wall extending from the centrum to the nuchal plates, 

 separating the right and left halves of that portion of the body above 

 the vertebral column. The parapophyses of these soldered vertebrce 

 present the most diverse forms, sometimes appearing as porous, 

 rounded prominences, as in Doras niger, at other times uniting and 

 forming a broad shield projecting from the sides of the coalesced 

 centrums, as in Perinampus typus. 



Intimately connected with this extraordinary condition of the ver- 

 tebral elements, are the modifications which we observe in the osseous 

 rays of the dorsal fin of these fishes. The lateral apophyses of 

 the interneural spine supporting the first fin rays, not only serve as 

 articulating surfaces for the bases of the rays, as is ordinarily the 

 case, but spread out into dermal plates, which unite together in a 

 singular manner to form a nuchal shield, to which Cuvier gave the 

 name of " bouclier." 1 



In Doras niger the united anterior vertebras are four in number, 

 the first three exhibiting modified parapophyses; in the third is seen 

 the first indication of a costal organization. 



The first centrum is quite small, and is closely united to the 

 basilar bone by a serrated suture. Its small, thin, neural spine rests 

 anteriorly against the prolonged occipital crest; posteriorly it is 

 united to the first neural spine of the next vertebra, and there rising 

 half way to the shield covering the neck, meets the point of the first 

 interneural spine. 



1 For a detailed description of the fin structure in the various families of fishes, 

 I would refer to a series of papers by Dr. Rudolph Kner, " Ueber den Flossenbau 

 der Fische," published in the Sitzungsberichte der Ivaiserliche Akademie der 

 Wissenschaften Wien, Vols, xli, pp. 807-824. 1860 ; xlii, pp. 232-260, 1860 ; xliii, 

 pp. 123-152, 1861; xliv, pp. 49-80, 1861. 



