585 ) 



XVII. On some Cretaceous Echinoidea from the Neighbourhood of Lobito Bay. 



By Professor J. W. Gregory, F.R.S., D.Sc. 



(MS. received June 2, 1915. Read June 28, 1915. Issued separately August 21, 1916.) 



Nine species of Echinoidea were described by de Loriol * from Benguella and 

 mainly from the neighbourhood of Dombe Grande. 



1. One of his species, Epiaster catumbellensis,t is common in the Lobito district. 

 It is recorded by de Loriol from the Inflata beds at Catumbella, and the younger 

 Cyprina ivensi sandstone at Dombe Grande. It is a variable species. According 

 to the dimensions given by de Loriol, the length varies from 25 to 36 mm., and the 

 breadth varies from 88 to 94 per cent, of the length and the height from 66 to 77 per 

 cent, of the length. His illustrations show that the species has two chief forms : in 

 one the shape is depressed and the posterior margin is nearly vertical ; in the other 

 the posterior interambulacrum is subcarinate, and the posterior margin is more sloping 

 owing to the projection of the lower posterior corner. In de Loriol's figure, pi. viii, 

 No. 4, the posterior margin has a slope of only 7° from the vertical ; in his fig. 5 this 

 slope is 15° from the vertical. 



I collected specimens of this species 50 feet above the algal bed at the Catumbella 

 dam, where it was below the level of the Inflata beds ; from marls with " S" inflata 

 at Old Lobito ; from some marly beds, in which it is abundant, in the upper part of 

 the Inflata zone ; and also from the Salenia bed and at a slightly higher level 

 (850 feet) above that bed. Many of the specimens are poorly preserved, and some 

 are found only as internal casts. The dimensions are therefore quoted, as they are 

 useful in the determination of the species. 



It is possible that two of the forms figured by de Loriol should be separated, but 

 they were both found together in Lobito. 



Specimens Collected.! 

 No. 292. Gorge near Old Lobito. 



1. Good internal cast. 1., 29 ; b., 26 ; h., 19| ; a depressed variety. 



2. 1., 29 ; b., 29 ; h., 17 ; very depressed variety. 



3. 1., 32 ; b., 32|- ; h., 25 ; broad high variety. 



4. Specimens with best-preserved granulation. 



* In Choffat and de Loriol, "Materiaux pour l'ttude stratigraphique et paleontologique de la province 

 d'Angola," Mem. Soc. Phys. Hist, Nat. Geneve, vol. xxx, 1888, 116 pp., 8 plates, 

 t Ibid., pp. 112-114, pi. viii, figs. 3-6. 



| Dimensions are in mm. :— 1. = length ; b. = breadth ; h. = height. 

 TRANS. ROY. SOC. EDIN., VOL. LI, PART III (NO. 17). 85 



