326 Messrs. Hancock & Atthey on. the Genoric Identitij 



Prof, M'Coy seems to think that his CUmaxodus imhricatus 

 is related to Pwcilodiis. The reLationship, however, with this 

 genus seems to us to be remote, though it may have some cha- 

 racters in common with Janassa. 



The bodies of these two fishes, Janassa and CUmaxodus, 

 were covered witli shagreen. In the former it is beautifully 

 preserved, the granules being highly polished, irregularly 

 rounded, with one side a little flattened and obtusely denticu- 

 lated. On the small slab, with numerous teeth of CUmaxodus, 

 already noticed, is a great quantity of granular matter, but 

 the granules are much disturbed ; a few, however, are well 

 displayed, and show considerable resemblance to those of 

 Janassa ; but the denticulations at the side are produced into 

 sharp points, and the surface is undulated. 



Although CUmaxodus Ungucefortms was pretty fully de- 

 scribed in the paper already referred to, we will make, on the 

 present occasion, some general remarks on the teeth in our 

 possession, and also redescribe them. 



The species cannot be considered common, though we have 

 obtained eighteen primary teeth in the shale at Newsham and 

 elsewhere, and eight of the secondary or Petalodontoid form. 

 The largest of the former is If inch in length, including the 

 root, and upwards of | inch wide at the broadest part. The 

 smaller are not more than f inch long, and are oblique : these 

 are the second primary teeth. There are three about this size 

 in the collection. We have one, however, wdiich, from its 

 obliquity, is undoubtedly a lateral tooth, that is only | inch 

 in length. They are ovate, depressed, with the broad extre- 

 mity anterior. The crown is upwards of two-thirds of the entire 

 length, and is divided into two portions, anterior and posterior ; 

 the former is a wide, hollow, arched, scoop-like cutting- 

 margin, which in some specimens is obscurely and minutely 

 crenulated or denticulated, and is usually quite sharp : this 

 portion occupies the anterior third of the crown ; the posterior 

 two-thirds is shield-formed, somewhat convex, with the point 

 directed backwards and the sides evenly arched outwardly, 

 This is the crushing- or grinding-surface, and is traversed by 

 strong transverse undulated ridges imbricated forward, and 

 divided by wide deep grooves. In fully developed specimens 

 there arc six sucli ridges: but the number varies, some having 

 four, others five ; and in the small, second lateral, oblique in- 

 dividuals there are only three. The ridges bend upwards at 

 the sides, and usually arch a little forward at the centre, 

 where they are most strongly undulated nnd sometimes deeply 

 notched and angulated, roughened :ind granulated. But they 

 vary considerably in these respects, some being almost smooth ; 

 and in one of our six'eimens all the ridges are comparatively 



