on the North Coast of Cormcall. 151 



are problematical. At first it suggested the idea that it might 

 iudicate a siphimcle, but there is no evidence that it was a hollow 

 tube. Mr. G. C. Crick, who has most carefully examined these fossils, 

 is imable to recognize in them any genuine Cephalopodan characters. 

 The real nature of these forms has been a subject of much 

 speculation alike to the writer and to other paleeontologists who 

 have examined them. They present several points of resemblance 

 to the Hyolithidce in their general form, size, the character and 

 ornamentation of the shell, and even the peculiar flaps or lateral 

 processes may be looked upon as analogous to the winged expansions 

 in Pterotheca, Salter, and Pterygotheca, Novak. I am unable to say 

 at present whether any structure occurs in known Hyolithidae 

 which can be compared with the interior rod-like body in Pteroconus. 

 On the whole there seems sufficient justification for regarding this 

 genus as belonging to the Hyolithidaj. The systematic position of 

 this family is still a matter of debate, and its relations to the 

 Pteropoda have not been certainly proved. 



Whilst working at the specimens sent to me by Mr. Howard Fox, 

 my attention was called to the figures of some casts of fossils from 

 Polruan, etc., by Mr. Upfield Green, in the Trans. Roy. Geol. Soc. 

 Cornwall, vol. xii (1899 j, pt. 4, pi. F, p. 227. Through the kindness 

 of Mr. Green and Mr. J. H. Collins, 1 had an opportunity of seeing 

 the originals of the figures which are preserved in the Museum 

 of that Society at Penzance, and at once recognized them as casts 

 of organisms similar to those discovered by Mr. Fox. Mr. Green 

 did not describe the forms, but limited himself to giving the figures 

 and naming " the fossil Nereitopsis cornuhicus, from its somewhat 

 distant resemblance to some of the species of the genus Nereis 

 (Cuvier) of the dorsibranchiate order of Annelids." I pointed out 

 to Mr. Green that the fossils themselves, as distinct from the casts, 

 precluded the idea that they could in any way resemble any species 

 of Nereis, and that consequently the name he proposed was mis- 

 leading and should be changed. Mr. Green accepted my suggestion 

 and desired to substitute Pteroconus for Nereitopsis, and I have 

 adopted his fresh name as that of the genus. Mr. Green states that 

 the larger of his specimens (fig. 1, pi. F) "differs from the other's, 

 being terminated posteriorly by a tuberculated extension," and this 

 may properly be considered as the type of Pteroconus (Nereitopsis) 

 Cornuhicus. Whether the other forms represented in his figures are 

 new species or will prove to be the same as those described and 

 figured in this paper must remain at present undecided. 



The specimens of Pteroconus mirus were collected by Mr. Howard 

 Fox in the claret - tinted and bluish shales, probably of Lower 

 Devonian age, exposed in the clift's and foreshore at Bedruthan 

 Steps, North Cornwall. Mr. Fox has announced his intention to 

 present the specimens figured to the British Museum (Natural 

 History), Cromwell Road, South Kensington. 



Pleuroclictyum, sp. (PI. VII, Fig. 11.) 



Corallura discoidal, thickness inconsiderable, the upper surface 

 depressed convex, diameter from 25 to 34 mm. There are about 



