FROM THE OLD RED SANDSTONE OF SHETLAND. 



325 



systematic position of Holonema, he very significantly compares Claypole's original 

 specimen with "the lozenge- shaped plate of Coccosteus; the ventro-median plate of Owen." 

 Professor Claypole in the following year returned to the subject in a paper entitled 

 " Palseontological Notes from Indianopolis."* Here he states that a second plate, 

 evidently a lateral one, had come into his possession, and also that Professor H. S. 

 Williams had obtained a new and unique specimen from the Catskill of New York, 

 consisting of several large plates of Pterichthys rugosus, Claypole. He gives a restored 

 outline of the cuirass, here reproduced, text-fig. 3, from which it will be seen that behind, 

 or supposed to be behind, the original central plate is a posterior median one, while 

 two pairs of lateral ones complete the sides. Quoting Professor Newberry's opinion 

 that the characters justify a separation from Pterichthys, he says that, " for the present, 



'mMw^ 



Fig. 3. — Ventral cuirass of Holonema rugosum, supposed by Claypole to be the dorsal shield of a species of Pterichthys or 

 allied genus. From Prof. Claypole's paper in the American Geologist quoted above. The nomenclature of the plates given by 

 him is — a, dorso-median (first described) ; c, dorso-lateral left ; b x post-dorso-lateral right ; b 2 , post-dorso-lateral left ; d, 

 post-dorso-median. 



According to Dr Smith Woodward's view, obviously the correct one! that this cuirass is the ventral shield of a Coccostean 

 turned the wrong way, these plates would read— a, median ventral ; d, anterior median ventral ; b± and b 2 , anterior ventro- 

 laterals ; c, posterior ventro-lateral. 



however, the matter must remain undetermined and the fossil be called Pterichthys 

 (Bothriolepis) rugosus or Holonema rugosum.'" It is, however, clear that Claypole still 

 believed in the Pterichthys theory, and also that he now looked on the plates in his 

 figure as being dorsal instead of ventral ; for he says, " The form of the central plate, 

 the presence of another median plate at its narrow end, the form, size, and fit of the 

 lateral plates at its wide end, the direction of the wrinkles, and the number of plates 



* American Geologist, vol. vi. (1890), pp. 255-258. 



