834 DR RAMSAY H. TKAQUAIR ON FOSSIL FISHES COLLECTED BY THE 



Description. — As yet very few examples of this species have occurred, and of these 

 not one is entire. The specimeu represented in PI. IV. fig. 3 shows a large portion 

 of the fish, but is imperfect both in front and behind : from what remains we ma} T judge 

 that its original length was seven or eight inches. The whole surface is closely covered 

 with minute, sharp, conical, striated spines, as seen magnified in fig. 4, and still further 

 enlarged in fig. 5. 



Badly preserved specimens of Thelodus Scoticus and Lanarkia spinulosa are some- 

 times difficult to distinguish from each other. 



Position and Localities. — Downtonian Beds at Seggholm and Birkenhead Burn. 



OEDEE OSTEOSTEACI. 



Family Ateleaspidje. 



Genus ATELEASPIS, n. g., Traquair. 



Imperfectly known. General form of body apparently as in the Ccelolepidse, but the 

 dermal covering in front consists of small polygonal plates, while behind the pectoral 

 fin-flaps it takes the form of flat rhombic sculptured scales. Orbits apparently on the 

 top of the head as in C&phalaspis. 



Ateleaspis tessellata, n. sp., Traquair. 

 Plate IV. figs. 6-12. 



In my preliminary report (p. 74) I referred to " one or two fragments showing quad- 

 rangular osseous scales belonging to some other fish," no doubt undescribed. On 

 account of the very fragmentary nature of those specimens I abstained from giving 

 them a name, as well as from entering any further into their description. 



Since that report was written, Mr Tait was successful in obtaining a specimen at 

 Seggholm, which I think I am justified in identifying with these fragments, and which, 

 imperfect as it is, throws a certain amount of light on what is apparently a very 

 remarkable fish. 



Description. — The most perfect specimen is represented of the natural size in PI. 

 IV. fig. 6, and shows the anterior portion, including the pectoral fin-flaps, in a tolerable 

 state of completeness ; the tail is, however, obliquely cut through on the right side. We 

 have here in front a contour essentially similar to that in Thelodus or Lanarkia, though 

 the pectoral flaps appear to be a little more rounded. When examined by a lens, the 

 surface appears covered with small polygonal tesserae, which are not all of the same size 

 or of the same number of angles, and these tesserae were evidently covered with minute, 

 closely-set, rounded tubercles. As there is scarcely any of the original bony matter left 

 in the fossil, a study of the counterpart is necessary towards coming to a conclusion as 

 to the condition of the surface. In the same Plate, fig. 9, we have a very little bit of the 

 counterpart magnified five times, showing distinctly the impression of the tesserae and 



