382 Mr. J. E. Gray on the Arrangement of 



2. B. Burmanica. Ph. B., Philijyn, Abbild. 1. 1. f. 1. 



3. B. Candida. Ph. c, Sow. Thes. f. 21-23. P. dactyloides, 



Chiaje. P. siHcula, Lamk. P. papyracea, Spengler. 



4. B. parva. Ph. p., Sow. Thes. f. 31, 32. Ph. crenulatus, So- 



lander in Spengler. P. dactylus, var. Desk. P. ligamentina, 

 Desh. P. dactyloides, Lamk. 



5. B. simiHs. Ph. s., Gi-ay, Sow. Thes. f. 12-14. Ph. antipo- 



darum, Philippi, Abbild. t. 1. f. 3. 



6. B. manillensis. Ph. va., Philippi. P. manillsej Sow. Thes. 



f. 17, 18. 



7. B. Ei-ythrsea, Grag. Shell ovate, elongate, radiately ribbed ; 



the central ribs rather distant, with slight distant tubercles ; 

 hinder ribs nearly obliterated ; the anterior ribs rather di- 

 stant, with acute imbricate spines ; the anterior gape broad, 

 ovate, short. 

 Hab. Red Sea. 



8. B. fragihs. Ph. f.. Sow. Thes. f. 92, 93. 



3. Dactylina, Gray, P. Z. S. 1847, 187. Thoanoa or Thovana, 



Leach MSS. 



* Nucleus of dorsal valve anterior, gape narrow elongate. 



1. D. orientalis. Ph. o., Gmelin. Ph. Siamensis, Spengler, Sow. 



Thes. f. 3, 4. Ph. dactylus, Solander MSS. 



2. D. Chiloensis. Ph. Ch., Molina, Sow. Thes. f. 1, 2. Ph. Cam- 



pechensis, Gmelin. 

 Var. P. laqueata. Sow. Thes. f. 19, 20. 



** Nucleus of dorsal valve posterior, gape broad. Dactylina. 



3. D. dactylus. Ph. d., Linn., Sow. Thes. f. 10, 11, 47. Ph. mu- 



ricatus, Da Costa. Ph. hyans, Pultney. P. callosa, Lamk. 

 Ph. tuberculata, Turton. 



4. Xylophaga, Turton, 1822. 



1. X. dorsalis, Turton, Sow. Thes. f. 103, 104. Ph. Xilophaga, 



Desh. 



2. X. globosa. Sow. Thes. f. 101, 102. 



b. Siphons naked at the base ; front gape of the valves large, at 

 length closed, with a callous plate. 



5. JouANNETiA, DcsmouUn, Bull. Soc. Linn. Bord. ii. 244; Rang, 



Man. 346. Pholadopsis, Conrad, Bull. Acad. Philad. 1849, 

 156. Triomphalia, Sow. Thes. 1850. Teredo, sp. Deshayes. 



* Valves with two impressed radiating grooves. 



1. J. globosa. Ph. glob., Quoy. T. globosa. Sow. Thes. f. 54, 55. 



2. J. Cumingii. Triomph. C, Sow. Thes. f. 56, 57. 



