GONATODUS PARVIDENS. 99 



3. Gonatodus parviuens, Traquair. Plate XXI ; Text-figure 3c. 



Gonatodus sp., Traquair, Geo]. Mag. [2], vol. viii, 1881, p. 34. 



— pauyidens, Traquair, Ibid., vol. ix, 1882, p. 546 ; Proc. Roy. Soc. 



Edinb., vol. xvii, 1890, p. 392; Trans. Roy. 

 Soc. Edinb., vol. xl, pt. iii, no. 28, pp. 695 and 

 696. 



— - A. 8. Woodward, Cat. Foss. Fishes Brit. Mus., pt. ii, 1891, 



p. 435. 



Specific Characters. — Maxillary bone having its inferior or dentary border nearly 

 straight or only slightly deflected posteriorly, its binder border nearly vertical, and its 

 superior border passing gently downwards and forwards into the forwardly directed 

 suborbital process ; teeth very small; scales large, the exposed area punctate, and in the 

 flank scales showing along the anterior margin a slight furrowed striation ; posterior 

 border of scales minutely serrated. 



Description. — This species, which sometimes attained a length of over eight inches, 

 resembles the two previous in general form and structure, though it differs in some promi- 

 nent details. The cranial roof-bones are ornamented with rather fine contorted raised 

 stria?, passing often into elongated or even rounded tubercles. The maxilla (PI. XXI, fig. 

 4 ; text-figure oc) differs in form from that bone both in punctatus and in macrolepis. Its 

 dentary margin is only very slightly deflected posteriorly, so that this appears nearly straight; 

 the posterior margin of the post-orbital plate is nearly vertical — in the specimen figured 

 in PI. XXI, fig. 4 it is even inclined downwards and forwards — the superior-anterior 

 margin passes gently downwards and forwards into the suborbital process. The teeth, 

 both in the maxilla and in the dentary part of the mandible (fig. 5) are very small, 

 though they retain the shape and arrangement characteristic of the genus. The scales 

 are proportionally large, as in G. macrolepis. One from the flank is represented in 

 fig. 3 ; its exposed surface is smooth and punctated all over, while in addition there are 

 close to and parallel with the anterior margin a few delicate furrows ; the hinder border 

 is minutely serrated. The fins do not seem to be specially large, and the aspect of their 

 rays is as in the other two species of the genus. Usually the joints are rather short, but 

 they appear somewhat elongated in the portions of fin represented in-figs. G and 7. In 

 fig. 6 the commencement of the fulcra along the anterior margin of the dorsal fin is 

 exceedingly well shown. 



Observations. — Gonatodus parvidens was first determined by me in 1882 from 

 detached maxillary bones from the Borough Lee Ironstone in my own collection, and 

 these accordingly constitute the types of the species. The occurrence of jaws and teeth 

 of the same form in more or less entire fishes from the same Ironstone confirmed the 

 reference of the species to the genus Gonatodus, and presently I referred to the same 



