Mr. F. Smith on the Genus Centris. 357 



Pholas crispata, L. Op. cit. iii. p. 112, v. pi. 53. f. 1. 



Abundant in the soft shale and sandstone at East and West 

 Rocks, and especially opposite the castle. Sometimes the 

 siphons are observed protruding through sand which coats 

 some of the ledges, liouug specimens are often cast ashore 

 on the West Sands in water-logged and decayed wood, whence 

 they are extracted by the sea-fowl. 



Genus 3. Xylophaga, Turton. 

 Xylophaga dorsalts, Turton. Op. cit. iii. p. 120, v. pi. 53. f. 4. 



Not common ; several living specimens occurred in the 

 wood of a submerged thorn tree. 



Order Solenoconchia. 



Fam. DentaUdae, H. & A. Adams. 



Genus Dentalium, L, 



Dentalium entalis^ L. Op. cit. iii. p. 191, v. pi. 55. f. 1. 



Occurs on the West Sands in a living state after some 

 storms. The specimens procured from the fishing-boats are 

 generally tenanted by Sipunculi. Common. 



[To be continued.] 



XLIX. — A Revision of the Genera Epicharis, Centris, Eulema, 

 and Euglossa, helonging to the Family Apidse, Section Sco- 

 pulipedes. By Frederick Smith, Assistant in the Zoolo- 

 gical Department of the British Museum. 



[Continued from p. 322.] 



Genus Centris. 



Centris (pt.), Fab. Syst. Piez. p. 354 (1804). 

 TrrtcAina, Klug, lUig. Map. vi. p. 226(1807). 

 Hemisia, Klug, ibid. p. 227 (1807). 

 Ptilotopus, Klug, Berlin Mag. p. 32 (1810). 



Generic characters. 



Head not so wide as the thorax ; eyes large, lateral, elongate- 

 ovate ; ocelli placed in a curve on the vertex ; antennse geni- 



