TAPES. 359 



pied the former burrow of a Pholas dactylus, has a 

 group of Serpula triquetra attached to it on the poste- 

 rior side, the hole being large enough to contain both. 

 This is a confirmatory proof that T. pullastra does not 

 perforate any hard substance. 



Although Mr. William Wood figured this species in 

 the f Linnean Transactions ' (vol. vi. 1. 17. f. 13, 14), and 

 showed that the structure of its hinge was different from 

 that in T. decussatus, he did not assign any specific name 

 to it. I believe our shell is the Venus literata of Linne 

 and Poli ; but that name is now used for a tropical spe- 

 cies. As I have before remarked, the V. geographica of 

 Chemnitz is the southern form or variety, to which the 

 V. eremita of Brocchi, V. hicolor, V. catenifera, V. reti- 

 fera, and Venerupis nucleus of Lamarck, and the Venus 

 Tenorii of Costa may also be referred. 



4. T. decussa'tus *, Linne. 



Venus decussate, Linn. Syst. Nat. p. 1135 (according to modern authors). 

 T. decussata, F. & H. i. p. 379, pi. xxv. f. 1. 



Body thick, oval, very pale cream- colour or greyish- white ; 

 margins having their edges scalloped or fringed with white : 

 tubes subeylindrical, separate throughout, and (at the will of 

 the animal) diverging in various directions, of the same length, 

 which when they are extended is equal to the breadth or 

 transverse admeasurement of the shell; they are at times 

 greatly distended ; their colour, to within a quarter of an inch 

 from the orifices, is pale yellowish-white, interspersed with 

 minute flakes of pure white, streaked or speckled near the 

 orifices with confused tawny-yellow, reddish-, or dark-brown 

 markings; orifices eD circled with cirri, that of the lower (or 

 alimentary tube) having about 12 long and as many alternate 

 shorter ones, and the upper (or excretal) tube being furnished 

 with about 20 equal-sized ones ; these cirri are of a brown or 

 bistre colour : gills suboval, pale brown sprinkled with minute 

 darker points ; as usual, the upper pair is the smaller ; they 



* Intersected by lines crosswise. 



