112 Mr. H. J. Carter on Fossil Sjyonffe-sptcules of 



in the ribs, from which they branch off laterally towards the 

 farrows. 



Mr. Davidson's specimens were taken in from 45 to 50 

 fathoms water, on the Agulhas Bank, south coast of Africa. The 

 locality has suggested to me the generic name which has been 

 given to the species. 



EXPLANATIOX OF PLATE XI. 



Fiff. 1. Natural -sized outline of Ayulhasia Davidsonii. 



Fig. 2. Same species, dorsal view, showing position of tlie foramen. 



Fig. 3. Same species, ventral view. 



Fig. 4. Same species, lateral view. 



Fig. 5. Same species, interior of dorsal valve, showing loop, teeth, and 



cardinal muscular fulcrum. 

 Fig. 6. Same species, profile view of the loop. 

 Fig. 7. Same species ; view of the interior of ventral valve and of the 



upper aspect of the beak, the latter showing the area («), del- 



tidium (b), foramen (c), infiexed sides of the beak (d), and one 



of the sutures bounding the area (e). 

 Fig. 8. Represents tubuli characteristic of Terehratidina cajmt-serjjcntis. 



I am very much indebted to Mr. Davidson for finishing ofi" my rough 

 sketches of the above fi^m-es. 



Xiy. — Oti Fossil Sjyonge-sjjicules of the Greensand comjKired 

 with those of existing Species. By H. J. Carter, F.R.S. &c. 



[Plates VII.-X.] 



The material which furnished the fossil sponge-spicules from 

 which all the figures, except three, in the accompanying four 

 plates were taken, was found by my kind and intelligent 

 friend Mr. W. Vicary, of Exeter, in the " Upper Greensand " of 

 Haldon Hill, near Exeter, and of Black Down, near Cullompton, 

 respectively, — the former portion in a stratum of greenish- 

 brown, loose, fine sand, about 25 feet thick, and the latter 

 in a rounded pebble of the same nature, more consolidated. 



They were brought to my notice by Mr. Vicary and my 

 friend Mr. Parfitt, also of Exeter, who read a valuable paper 

 on them at the meeting of the '' Devonshire Association for 

 the advancement of Science, Literature, and Art," in July 

 last, which was subsequently printed in their ' Transactions ' 

 for 1870. 



The frequently loose state of the whole material, in which 

 the spicules are sometimes almost as numerous as the grains 

 of sand among which they are imbedded, together Avith their 

 large size, render their extraction with a simple but powerful 

 lens and a hair-pencil a work of time rather than one of dif- 

 ficulty. 



