164 Dr. Henry Woodtoard — On Penceus Sharpii. 



and did not erode it : if further the alluvium was derived from the 

 district in which it was laid down. As the major part of what has 

 been written on the " Glacial Epoch " rests on preconceptions and 

 d priori anticipations as to what ice would do, I shall not discuss 

 the evidence on which even authoritative statements have been put 

 forth. My wish is to learn how the 100 feet of Till were accumu- 

 lated : for even if they were piled up under a thinning glacier, it 

 still remains to be explained how so vast a quantity of detritus 

 could have been won from a small area by an agent steadily di- 

 minishing in force. 



IV. — Note on Pen^us Searpii, a Maorukous Decapod Ckusta- 



CEAN, FKOM THE IJPPER LlAS, KiNGSTHORPE, NEAR NORTHAMPTON. 



By Henry "Woodward, LL.D., F.E.S., etc. 



(PLATE IV.) 



IN a paper on the Lias of Ilminster, by my friend Mr. Charles 

 Moore, F.G.S., communicated to the Somerset Natural History 

 Society, and published in their Proceedings (1865-6, vol. xiii. p. 72), 

 I gave a list of the Crustacea submitted to me for examination by 

 Mr. Moore, among which was a species belonging to the genus 

 Penceus, referred by me to P. latipes, Oppel, from the Upper and 

 Middle Lias of Ilminster. 



In my fourth Eeport " On the Structure and Classification of the 

 Fossil Crustacea," presented to the British Association (Section C. 

 Geology), at the Norwich Meeting, August, 1868, I noticed the 

 occurrence of a second British species belonging to this genus from 

 the Lias of Northamptonshire, and named by me Penceus Sharpii. 



The following is an extract from my Eeport, p. 74 : — " I have 

 now to notice another species of the genus Penceus of Fabricius from 

 the (Lower ') Lias of Northampton. This is a remarkably per- 

 sistent Torm, and the genus is actually found now living in the 

 Mediterranean if Dr. Oppel's determination be correct, which I feel 

 little doubt in endorsing.^ 



"This handsome Crustacean" (see Plate IV.) "was not less than 

 9^ inches in length when measured along the dorsal line, the 

 carapace being about 3 inches, and the abdomen 6^ ; the rostrum 

 was very strongly serrated, as in the Palcemonidce, but the serrations 

 have been abraded in the fossil. 



" This form most nearly resembles in size and appearance the 

 Penceus speciosus of Miinster, but differs slightly in the form of the 

 border of the abdominal segments, and also in the direction of the 

 strong and deeply-forked sulcus which marks each side of the latero- 

 anterior portion of the carapace near the base of the great antennas. 

 The surface of the carapace and segments was highly enamelled, 

 some portions of which may still be observed in the fossil. 



1 This shoiild be Upper Lias. 



^ Dr. Oppel has described iive species belonging to the genus Penceus. One 

 (P. Liasicus) from the Lower Lias of Schambelen and four from the Lithographic 

 Stone of Bayaria. 



