The Genus Porosphcera, Steinmann. By George J. Hinde. 13 



These tubes are generally considered to have been occupied 

 originally by some organic body, such as the stem of a sea-weed, 

 not capable'of preservation as fossil, round which the Porosphcera 

 lived and grew. They are now found solidly infilled with the 

 soft chalky matrix which can readily be extracted. 



A further interest is attached to these naturally perforated 

 examples of Porosphcera from the fact that similar forms have 

 been found in association with the remains of the " Kiver-Drift " 

 folk, and it has been surmised * with much probability that they 

 may have been used by them for personal adornment, such as 

 necklaces, etc. 



P. IVoodwardi, Carter, is generally of a rounded form with one 

 or more slightly projecting peaks ; the base is small, concave, and 



* Kigollot, Mem. sur des Instruments en Silcx, etc., Amiens, 1854, p. 16 ; Parker 

 ami Jones, Ann. and Mag. Nat. Hist., ser. 3, vi. (1860) p. 3D ; James Wyatt, Geologist, 

 v. (1862) p. 233 ; T. Bupert Jones, torn, cit., p. 236 ; Sir C. Lyell, Antiquity of 

 Man, 1863, p. 110, fig. 15 ; 4th ed., 1873, p. 165; Worthington Smith, The Primitive 

 Savage, 1894, p. 272 ; Sir John Evans, Ancient Stone Implements of Great Britain, 

 2nded. 1897, p. 657. 



Explanation of Plate I. — continued. '■ 



Fig. 19. Porosplaera Wocdicardi, Carter, sp. Showing the branching surface canals. 

 X 2 diam. Zone of Hula ster subglobosus; Dover. Collection of Dr. 

 Eowe. 



„ 20, 20a. Porosphrra pileolus. Thimble-shaped specimen, with a fragment .of 

 dermal layer on the exterior ; the base (20a) showing concentric 

 bands of growth. Zone of A. quadratus ; near Newhaven. Col- 

 lection of Dr. Eowe. 



., 21,21a. Ditto. Zone of Marsupites (JJintaerinus Band); Thauet coast. Col- 

 lection of Dr. Eowe. 



,. 22,22a. Porosphxra patelliformis, sp. n. Viewed in profile (22); the deeply 

 concave base (22a) showing concentric lines of growth and faint 

 radial lines. Zone of A. quadratus ; Sussex coast. Collection of 

 Dr. Eowe. 



., 23, 23a. Ditto ; a couical specimen, viewed in profile (23) ; the base with faint 

 concentric lines of growth (23a). Zone of Marsupites {JJintaerinus 

 Band) ; Thanet coast. Collection of Dr. Eowe. 



„ 24,24a. Ditto; a depressed specimen, viewed in profile (24); the base with 

 concentric and radial lines (24a). Same zone and locality as the 

 preceding. Collection of Dr. Eov. r c. 



., 25. Ditto; view T ed from above, showing some fragments of the spicular dermal 

 crust. Same zone and locality as the preceding. Collection of 

 Dr. Eowe. 



,. 26. '26a. Ditto; a small specimen, viewed in profile, natural size (26); and the 

 concave base, with rod-like spicules radiating from the centre to the 

 margins, enlarged 4 diam. (26a). Zone of Terebratulina gracilis ; 

 East Cliff, Dover. Collection of Dr. Eowe. 



„ 27, 27a. Forosphxra arrecta, sp. n. Viewed in profile (27), and showing the 

 base (27a), enlarged 3 diam. Zone of Rhynchonella Cuvieri ; Brans- 

 combe Cliff, South Devon coast. Collection of Dr. Eowe. 



,, 28, 28a. Ditto ; showing the exterior and the basal aspect, enlarged 3 diam. 

 Zone of Marsupites (JJintaerinus Band); Thanet coast. Collection 

 of Dr. Eowe. 



