﻿RHIZODONTID.E. 359 



Type. Imperfect fishes ; British Museum and Forres Museum. 



The tj-pe species, attaining a maximum length of about 0-3. Head 

 with opercular apparatus contained about four and a half times in the 

 total length ; parietal region equal to the fronto-ethmoidal in length, 

 and the upper part of the anterior extremity of the snout covered 

 with separate polygonal plates ; jaws much elongated. Pelvic fins 

 arising in advance of a point midway between the operculum and 

 the extremity of the tail; dorsal fins higher than long, the first 

 smaller than the second, and the latter about equal in size to the 

 opposing anal. Scales small. 



Form. 6f Loc. Lower Old lied Sandstone : Nairnshire, Banffshire, 

 and Orkney \ 



P. 340. One of the type specimens figured by Agassiz, op. cit. 

 pi. xxi. a. fig. 3 ; Lethen Bar, Nairnshire. Egerton Coll. 



50104. Fish, in counterpart, showing portions of several head and 

 opercular bones, the clavicles, and fragments of the fins ; 

 Lethen Bar. The inner ridge upon the scales is very 

 prominent. Purchased, 1879. 



41891. Head and abdominal region of small fish; Tynet Burn, 

 Banffshire. Purchased, L870. 



43014. Small fish, in counterpart, showing the obtusely lobate 

 pectoral fins and portions of the pelvics, dorsals, and anal, 

 but wanting the caudal fin ; Tynet Burn. 



Purchased, 1871. 



43271. Small fish showing portions of the fins ; Tynet Burn. 



Purchased, 1871. 



36071. Scattered scales and various bones of a large fish ; Tynet 

 Burn. Purchased, 1861. 



P. 4045. Large well-preserved fish, 0*3 in length, in counterpart; 

 Gamrie, Banffshire. The head is vertically crushed, and 

 one side of the counterpart exhibits the cranial roof 

 from the inner aspect, while the other gives an imperfect 

 inner view of the principal jugulars. The parietal and 

 fronto-ethmoidal regions of the cranial roof are well sepa- 

 rated by a transverse suture ; and there is a median suture 

 between the frontals, marked at one point either by a large 

 excavation on the inner surface of the closely apposed bones, 

 or by a foramen, such as exists in Osteolepis and Diplopterus. 



1 Fragments from the Devonian of Livonia are also assigned to this species by 

 E. von Eichwald, Leth. Eossica, vol. i. (1860), p. 1564. 



