Dr. R. H. Traqnair — On Drepanaspis. 



155 



though scarcely bilobed caudal fin, but there is no trace of any other 

 fins or appendages, paired or unpaired. These parts are covered 

 on the sides by rhombic tuberculated scales, and bordered above and 

 below respectively by a single row of narrow imbricating median 

 scales or 'fulci'a.' Nothing resembling Jin-rays can be seen, nor is 

 there any definite line of demarcation between the scales of the 

 body prolongation and those of the fin-membrane, though the latter 

 become gradually smaller. 



Turning now to the ventral surface of the animal, I have in Fig. 2 

 given an accurately reduced sketch of the plates as seen in the 

 new specimen to which I have alluded, while Fig. 3 represents 

 a restoration in which the oblique distortion due to slaty cleavage- 



^P.l. 



f>v.l. 



Fig. 2.- — Sketch of a specimen of the carapace of Drepanaspis Gmilndencnsts, 

 Schliiter ; one-third natural size ; distorted by slaty cleavage, and somewhat 

 imperfect behind, o. mouth; r. rostral or upper labial plates; e.l. external 

 labial plate ; m. mental plate ; x. sensory plate ; a.v.l. anterior ventro- 

 lateral ; m.v. median ventral ; m.d. portion of inner surface of median 

 dorsal ; ^;.i'.^. posterior ventro- lateral ; p.l. postero -lateral or cornual plate. 



has been corrected. We may now see that the mouth (o.) is placed 

 exactly where I had expected to find it, namely, at the anterior 

 margin of the carapace. It is a transverse slit, the upper margin of 

 which is formed by the anterior edges of the rostral plates (r.) already 

 mentioned, while at each outer corner there is a small external labial 

 plate (e.h), the tubercles on which are rather larger than those 



