On the Scattered Skeletal Remains of Holothuroidea. 197 



central space large and solid; perforations of outer zone, 

 varying from eight to twelve in number, nearly circular. 

 Diameter of plates from -01 to "0105 inches ; central space 

 has a diameter of '0035 inches, and the side perforations 

 from -002 to -0025 inches. 



Ohs. — This again appears to be a clearly distinct type from 

 either of the preceding forms. It may be recognised by the 

 increased number of perforations in the outer zone, their 

 circular form, and the large circular fiUed-in space. The 

 margin is much more undulating than in C. (?) Traquairii, 

 the undulations corresponding to the perforations. 



Examples sometimes occur with only the central part re- 

 maining, wdien they present a simple, multi-stellate appear- 

 ance (PL VI., Fig. 7). 

 Loc.and Horizon. — Eiver Avon, below Kinneil Mill, as before. 

 Description of the Plates. 



Plate V. 



Fig. 1. Portion of a plate of Achistrum Niclwlsoni, probably from near the 

 centre, showing the larger perforations, Woodend Quarry, near Fordel. 



Fig. 2. An almost entire plate of the same species, showing the gradation 

 in size of perforations towards the undulate margin. Woodend Quarry. 



Fig. 3. Portion of a plate (^c7m^rM7>i ? sp.), with perforations of interme- 

 diate size. Woodend Quarry. 



Fig. 4. Larger portion of an incomplete plate, with the smallest size of 

 perforations {Achistrum ? sp. ). Woodend Quarry. 



Fig. 5. Two almost entire plates of A. Niclwlsoni, with, lying between 

 them, one of its hooks. Woodend Quarry. * 



Fig. 6. Portions of another plate with the hook exposed in situ. Kinneil 

 (R. Avon). 



Fig. 7. Two of the hooks of A. Nicholsoni ; a, fully developed individual ; 

 h, incomplete example ; c, eye at proximal end of shank, Woodend Quarry, 



Fig, 8. A small tooth-like organism found associated with these minute 

 fossils. Woodend Quarry. 



Fig. 9. Quadriradiate spicules, enlarged towards the ends of the branches, 

 and Mdth the centre occupied by four perforations, one corresponding to each 

 branch of the spicule. Woodend Quarry, 



Fig. 10. Another form of the same, from the same locality. 



Fig. 11, Spatulate body, with fine transverse imbricating lines, of doubtful 

 nature, Woodend Quarry. 



Fig. 12. Triangular plates with serrate edges, and imbricating transverse 

 lines, having a certain resemblance to plates in the body of Cuctcmaria 

 frondosa. Woodend Quarry. 



Plate VI, 



Fig, 1. Cheirodota {?■) Traquairii, single plate showing semicircular perfora- 

 tions and four triangular ones. Woodend Quarry. 



