294 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



incumbent sands at Atherfield, I shall suppose my readers to be ac- 

 quainted with what is there stated, and also with the general characters 

 of the Wealden and its fossils. 



1. The ^^ Lower Perna Bed^' rises on the shore a few yards east 

 of a point immediately under the signal-staff of the Coast-Guard 

 Station, which is taken as the zero for distances hereafter men- 

 tioned eastward. Its thickness is about two feet and a half ; it varies 

 in composition from the state of dark blue sandy clay, or mud, to 

 that of greenish sand. It is easily diffused in water, and when ex- 

 posed to the sea is soon carried away, differing in this respect from 

 the bed immediately above ; but when both are dry, and seen toge- 

 ther in the face of the cliff, they are scarcely distinguishable. Perna 

 Mulleti is found in great numbers in both of these lower beds 1 and 

 2, and has not yet been found anywhere else. Among the other 

 fossils are beautiful specimens of Thetis, a genus which recurs 

 throughout the series here, from No. 1 up to 45, ov perhaps even 

 above the latter number. Large specimens of Gryphcea sinuata in 

 single valves, with a strongly marked carina, are found in this lower 

 ]3ed ; a proof that the species must have existed for some time during 

 or before its deposition. 



The remains of fishes, chiefly teeth and small fragments of bones, 

 are mixed with coarse quartzose gravel at the bottom of this bed ; 

 and occurring thus immediately over the Wealden, or even in contact 

 with it, it is not unreasonable to suppose that the fish were killed by 

 the change from fresh water to salt. 



Sir Philip Egerton, who has been so good as to examine some of 

 the fragments of teeth and bones which I found here, informs me, 

 that they include remains of the following genera of fishes, — Lamna, 

 Odontaspis (a gault species), SaurocephalMs, Hypsodon, Sphenon- 

 chusV.y Hyhodus, — and with these are vertebrae of a fish, and a very 

 small digital phalanx, supposed by Prof. Owen to belong to a Saurian. 



2. The "Upper Perna Bed" differs from the lower chiefly in com- 

 pactness and durability, to which qualities the prominence of Ather- 

 field Point may probably be ascribed. It serves as a sort of oblique 

 girder, giving solidity to the whole mass, and in fact is the only con- 

 tinuous bed of stone (if it deserves that name) which exists in this 

 neighbourhood, all the other stony masses being nodular and detached. 



The top of this bed rises on the shore about 520 feet east from 

 a point beneath the flag-staff of the Coast-Guard Station*. Its 

 final outcrop is visible in the cliff-top far westward, over the upper beds 

 of the Wealden. It runs out into the sea as a ledge visible at low 

 water, and its continuation at greater depths is well-known to the fish- 

 ermen, from their catching crabs upon it. This prolongation is called 

 "the Bench," and has been traced by land-marks to a distance of 



den clay with its freshwater shells, and above containing Perna Mulleti, GrypJKsa 

 sinuata, Panopcea," &c. 



[In a late visit to this place, I found all the coast covered with ruin, the con- 

 tact entirely concealed, and the strata distinguishable only in a few detached 

 points.— 5'ejt?/. 1844.] 



* The concealment of the strata during all my subsequent visits to the coast 

 prevented my verifying this distance, of which I have some doubt. 



