218 E. D. Weill iirn— Fish Fauna of Millstone Grit. 



D Shales of the Middle Grits at Wadsworth Moor, Yorkshire, and 

 there is also a tooth in the Woodwardian Museum, Cambridge,^ 

 which shows the characters of the above species. It is from the 

 same locality and horizon. 



Family PEISTODONTID.^, 



Geuiis PEISTODUS, Davis {ex Agassiz MS.), 1883. 



Pristodus falcatus, Davis, 1883. 



I have found one tooth of this species. 



Form, and loc. : D Shales, Middle Grits, Summit. 



Family COCHLIODONTID^. 



Geuus PSEPHODUS, Agassiz, 1862. 



Psephodus, sp. nov. 



Among the fish remains from Summit there is a series of three 

 lower (?) dental plates of Psephodus, having the following characters, 

 viz. : — The plates increase in size from before backwards, and 

 have the following measurements : anterior plate, anterior posterior 

 measurement 0-0008 m., transverse 0-0015 m.; median plate, anterior 

 posterior 0-001 m., transverse 0-002 m. ; posterior plate, anterior 

 posterior 0-001 m., transverse 0-0025 m. The margins, where 

 the teeth are in juxtaposition, are nearly straight, the anterior 

 one being very slightly convex, whilst the posterior one is very 

 slightly concave ; the posterior margin is greater in transverse 

 measurement than the anterior ; the outer margin is straight, the 

 inner one gently curved throughout its length. The crown is gently 

 arched from side to side, and the anterior external angle being 

 somewhat inrolled gives a slight obliquity to the coronal ridge. 

 The crown is covered with a dense layer of ganoine. The base 

 is thick and strong, and conforms with the surface of the crown. 



Kemarks. — Although the plates are so small, their characters are 

 so well displayed that I am not inclined to consider them as plates 

 of a young fish, but rather, from the fact that they do not appear 

 to agree with the specific diagnosis of any of the known species of 

 Psephodus, I am inclined to treat them as dental plates of a new 

 species, for which, on account of their small size, 1 propose the 

 specific designation minuta. 



Form, and loc. : D Shales, Middle Grits, at Summit. 

 Genus PCECILODUS, McCoy {ex Agassiz), 1855, amend. A. S. W., 1889. 

 Poecilodus Jonesii, McCoy, 1855. 



Anterior half of a dental plate. 



Form, and loc. : D Shales, Middle Grits, Summit. 



Family CESTEACIONTID^. 



Genus OEODUS, Agassiz, 1838. 

 Orodus elongatus, Davis, 1883. 

 I have found two well-marked teeth of this species, one being 

 almost identical with 0. elongatus, the other with O. angustus, as 

 figured by the late Mr. J. W. Davis, F.G.S.'' 



Form, and loc. : D Shales, Middle Grits, Summit. 

 1 Wellburn, op. cit. ^ Traus. Roy. Dublin Soc, vol. i, sect. 2, pi. li, figs. 1, 4„ 



