968 CLASS PISCES. 



second is behind the anal, the figure being incorrect in the latter 

 respect. Fin-spines from the Devonian of Canada, described as 

 Ctenacanthus and Homacanthus, are referred by Mr Woodward to 

 Climatius. 



Incert^e Sedis. — Here may be noticed the family Tarrasiidce^ 

 proposed by Dr Traquair for the imperfectly known genus Tarrasius, 

 from the Scottish Carboniferous, which is regarded as indicating an 

 aberrant type. 



B. Euganoid Series. — The remaining members of the order 

 include its typical representatives, and may be collectively known 

 as the Euganoid series or the Ganoidei Veri. 



Suborder 4. Crossopterygea. — In this group the pectoral, and 

 sometimes the pelvic, fins consist of a central lobe surrounded by a 

 fringe ; there is an infraclavicular in the pectoral girdle ; the rays of 

 the dorsal and anal fins are often more numerous than the support- 

 ing interspinous bones ; the preopercular extends forwards on the 

 cheek ; branchiostegal rays are replaced by jugular plates ; the de- 

 velopment of the vertebral column varies ; the tail may be either 

 diphy- or heterocercal, and the scales cycloidal or rhomboidal. This 

 suborder is the most primitive of the true Ganoids, among which 

 it holds a position somewhat analogous to that occupied by the 

 Ichthyotomi in the Elasmobranchei. 



Family Holoptychiid^:. — In the type family the pectoral fins 

 are acutely, and the pelvic subacutely, lobate ; the skeleton of the 

 former, according to Dr Traquair, being a biserial archipterygium 

 like that of Ceratodus. The teeth are of the so-called dendrodont 

 type, the dentine of the base being infolded 

 in an extremely complex manner, with cross- 

 branchings which form an intricate network 

 within the crown. The scales are cycloidal, 

 thick, and sculptured ; and there are two 

 dorsal fins, and a heterocercal tail in which 

 the inferior rays are much longer than the 

 superior. Before noticing the typical forms 

 we may briefly mention the genus Onychodus^ 

 from the Devonian of North America and 

 dus S sigmoidesT from thTi)e- Europe, which Dr Newberry considers may 

 (After n Ne wbe?r y r .) h ^"^ be allied to this family. The scales (fig. 

 901) have distinct ridges, and the mandible 

 has a presymphysial production furnished with teeth arranged some- 

 what like an old-fashioned cavalry spur. The type genus Holo- 

 ptychius (fig. 902) comprises fishes, which are often of large size, 

 from the Devonian of Europe and North America. The two dorsal 

 fins are placed in the hinder part of the body directly over the pel- 

 vic and anal. We may probably place here the imperfectly known 



