544 PKOP. E. W. CLAYPOLE OK THE STKITCTFEE 



of fishes of Silurian and Devonian age. As defined by him, they 

 were distinguished by the number of pieces composing the shield, 

 which in Pteraspis was seven or perhaps eight, in CyatJiasjpis four, 

 and in Seaphaspis only one. 



The dawn of new light on this subject came in the year 1872, 

 four years after the appearance of Lankester's masterly monograph. 

 In that year and in the ' Zeitschrift der Deutschen geologischen 

 Gesellschaft ' (Band xxiv. p. 1) was published a posthumous paper of 

 Dr. Kunth's containing a description of a specimen which he had been 

 fortunate enough to obtain in a block of Silurian limestone in a railway- 

 cutting near Berlin. The fossil consisted of a shield of Cyathaspis 

 (Lk.) and one of Scaphaspis (Lk.) facing it, both with the convex 

 sides outwards, indicating that they retained the positions in which 

 they had been situated during life, and at once suggesting the 

 inference that the latter was not an independent species, but only 

 a portion of the defensive armour of the animal represented by the 

 former. This was the first published announcement of any such 

 relationship between these fossils which rested on a base better 

 than suspicion, if, indeed, it may not be considered absolutely the 

 earliest guess of such relationship. Lankester, it is true, in his 

 monograph called attention to the fact that certain species of the 

 two genera Cyathaspis and Pteraspis are frequently found asso- 

 ciated with certain species of Scaphaspis, but failed to draw the 

 inference of their organic connexion, and, indeed, later he opposed 

 the view when brought forward by Kunth. 



For this there was some justification in the peculiar use which 

 Kunth made of his discovery. After he had, by most careful 

 working-out of the specimen from the matrix, convinced himself 

 beyond all reasonable doubt that the two shields really belonged to 

 one another, and held in the fossil the relative positions which 

 they had held in the living fish, he abandoned the safe ground on 

 which he had thus far travelled, and, led astray by what was little 

 better than a fancy, he wandered into regions in which he soon 

 lost his way. Failing to rely confidently, as he should have done, 

 on the strong evidence afforded by the microscopic structure of the 

 plates, he adopted the notion that they represented the head-shield 

 and pygidium of a roUed-up trilobite or trilobitic crustacean 

 belonging to a family not yet recognized by palaeontologists. He 

 likened it to a Calymene or Asaphus, — genera often found in this 

 folded condition. This view he confirmed by imagining that he 

 saw in some loose fragments on the slab the disjointed body-rings 

 of the same animal. Of course this opinion compelled him to 

 reverse the direction of the Scaphaspid shield, and make what was 

 considered by Lankester the front to be really the back, but as the 

 true nature and position of Scaphaspis in the fish was unknown 

 he encountered no logical obstacle in so doing. We will return to 

 this matter later. 



