1855.] BANKS — TILESTONES OF KINGTON. 97 



width. The Hthological composition of the bed overlying this layer is 

 that of the old red sandstone, — a coarse-grained micaceous grey stone, 

 altogether unlike the tilestone-beds. Above the bone-bed at Ludford 

 we noticed in the tilestone-beds near the surface Lingula cornea. 



The range of the Fterygotus has been shown to extend low in the 

 Ludlow Rocks*. I have met with only one trace of it below the 

 tilestones, — in the shales on the side of the descent of Knill Garra- 

 way, which contain Cardiola interrwpta, Graptolithus Ludensisy and 

 Orthoceras primcevum. This specimen, viewed with the naked eye, 

 appears nothing more than a black marking of an inch in length ; 

 with the aid of the microscope scales of Fterygotus appear ; but 

 there is nothing to indicate to what part of the animal it belonged. 

 The specimens in my possession prove that the Fterygotus was more 

 abundant in the Tilestones than in any of the underlying strata. 



The Fterygotus of the Tilestones is probably identical with the 

 Fterygotus so graphically described by Mr. H. Miller in the eighth 

 chapter of his * Old Red Sandstone.' It was a lobster-like animal 

 with a flexible tail, composed of several segments and probably ter- 

 minated by natatory fins. Mr. Miller considers that the terminal 

 flap of the tail was entire ; but it is possible that he may have con- 

 sidered as the terminal flap one of the curiously edged segments 

 presenting on the upper and under side a convex surface covered with 

 scale-like markings. 



The Fterygotus possessed two most distinctive features, which are 

 wanting in Limulus : a flexible tail, composed of segments, and a series 

 of regular jaw-feet ; while the only species of Limulus f known have, 

 as a caudal appendage, a straight pointed stylet without joints, and, 

 in common with many of the Foecilopoda%, have, as a substitute for 

 jaw-feet, spiny appendages at the base or haunches of the first six 

 pairs of feet. 



In the specimens of the joints, which formed the base of the feet 

 of Fterygotus, there is no vestige of any such appendage. I think I 

 may therefore venture to differ from the generally received opinion 

 that Fterygotus was one of the Foecilopoda, allied to Limulus of the 

 Indian Seas. 



The illustrations § accompanying the present notice contain three 

 distinct jaw-feet, with some of their appendages, — joints of some of 

 the first pairs of feet, — fingers of the forceps, — portions of the cara- 

 pace, — and a few segments of the tail, with the natatory appendages. 



* " Siluria," p. 142, 237, 346 ; Strickland and Salter, Quart. Journ. Geol. Soc. 

 vol. viii. p. 386 ; Symonds, Edin. New Philos. Journ. April 1855. 



f See Cuvier, Le Regne Animal ; Les Crustaces, par M. Milne-Edwards ; p. 249 

 et seq. and plate 76. 



X " Mais c'est surtout par I'absence de mandibules et de maehoires ordinaires 

 qu'ils (JPcecilopoda) s'eloignent de tous les autres Crustaces;" ibid. p. 247. 



§ Mr. Banks's beautiful drawings of the several portions of Pterygoti contained 

 in his collection are not reproduced with this memoir, but have been at his request 

 transferred to the Museum of Practical Geology for the illustration of the descrip- 

 tion of Fterygotus which is intended to be published in the Memoirs of that Insti- 

 tution. — Ed. Q. J. 



