532 Geological Society : Mr. D. Sharpe on the 



some object striking the surface of the sand with considerable impe- 

 tus. They may often be seen to cut through the ridge of one ripple- 

 mark, and after disappearing in the depressed interval, they are again 

 seen pursuing their former direction across the next ridge. They 

 may have been caused by fish swimming with velocity in a straight 

 direction, and occasionally touching the bottom with the under part 

 of their bodies. 



2nd. Small irregular pits averaging one-fourth of an inch wide 

 and one-eighth of an inch deep. These might have been caused by 

 some small animal probing the mud and turning up the surface in 

 quest of food. Mr. Strickland conjectures that some of the numerous 

 species of fish found in the bone-bed may have produced them, the 

 heterocene form of tail common to most of which, Dr. Buckland has 

 suggested, enabled them to assume an inclined position with the 

 mouth close to the ground. 



3rd. Narrow deep grooves, about one-twelfth of an inch in width, 

 the sides forming an angle at the bottom, irregularly curved and 

 often making abrupt turns, apparently formed by a body pushed 

 along by a slow and uncertain movement, such as might arise from 

 the crawling of Mollusks. Mr. Strickland refers them to the loco- 

 motion of Acephalous Mollusca, and supposes that the only shell 

 found in this bed, a small bivalve named by him Pullastra arenicola, 

 might have produced them*. 



4th. A tortuous or meandering track consisting of a slightly raised 

 ridge about one-tenth of an inch wide, with a fine linear groove on 

 each side. These tracks are analogous to those formed by the 

 crawling of small annelidous worms, as may often be seen on the 

 mud of the sea or fresh water. 



About eleven feet above the stratum which presents the impres- 

 sions above described, a second ossiferous bed occurs at Wainlode 

 Cliff, which escaped Mr. Strickland's notice in the section formerly 

 given (Geol. Proc. vol. iii. p. 586). It is a band of hard, grey, 

 slightly calcareous stone, about an inch thick, containing a plicated 

 shell resembling a Cardium, and scales and teeth of Gyrolepis tenui- 

 striatus, Saurichthys apicalis, Hybodus Delabechei, Acrodus minimus, 

 and Nemacanthus monilifer, all of which occur in the true " bone- 

 bed" below. On the upper surface of that bed are numerous im- 

 pressions, termed by Mr. Strickland fucoid, consisting of lengthened 

 wrinkled grooves, variously curved, about three quarters of an inch 

 wide, one-eighth Of an inch deep, and of variable length. The 

 bone-bed seems to be a local deposit, not being met with in the 

 other localities examined by the author, and being confined to a 

 portion only of Wainlode Cliff, where it constitutes No. 9. in the 

 following corrected section : — 



* Mr. Strickland describes this species as follows : — " Its form is nearly 

 a perfect oval, depressed, nearly smooth, but with faint concentric striations 

 towards the margin. The apex is about halfway between the middle of tbe 

 shell and the anterior end. The general outline closely resembles that of 

 the recent Pullastra aurea of Britain. Maximum length 7 lines, breadth 

 4£ lines, but the ordinary size is less." 



