138 BURMA, ITS PEOPLE AXD PRODUCTIOXS. 



incoi-poratcil with the protecting tube, as in Aspfrrjillum, o\ one valve only is free, 

 as in ClaratjcUa, or else both valves arc free, as in Gaxtrocliatna. 'J'he tiilies tlicmselves 

 are usually buried with the thickest end downwards in the mud or sand near low- 

 water mark. 



Gasteoch^na, Lamarch (not Spengler). 



Shell with both vahes free, cuneiform, equivalve, widely gaping in front, closed 

 behind, valves veiy ino(iuilateral. Ligament external. Tube calcareous, elaviform, 

 free or fixed. Yalves free, widely gaping in front. The shells are often inclosed 

 in strong flask-shaped tubes, attached to shells in which the animal burrows. 



* ,, LAGEXA, Lam. 



* ,, APEBTISSIMA, Dcsh. 



* ,, ciJiBruM, Eetz. 



Gastrocliana mumia, Spongier, or the Fistulana chva, Lam., as it is generally 

 called, is a curious shell, whose clavate tubes are found associated gregariously 

 at low-water mark at Singapore and in the Eastern seas, the tips only of the tubes 

 projecting, whilst their thick and closed ends arc deeply buried in the mud. 



AsPEEGiLLUM, Lamarcli. 



Shell small, oval, equivalve, glued to the walls of the tube, the umbones only 

 being visible. Open posteriorly or above. Clavate anteriorly or below, and closed 

 with a convex disk, pierced with tubular holes and with a minute central fissure, 

 and a handsome peripheral ring of tubes. The upper or siphonal cud plain or fiilled. 



* ,, spAHsuM, Sow. 

 The watering-pot shell. 



Few people who have admired the curious tubular shell ending in a disk, pierced 

 with holes like a garden watering-pot, are aware tliat the occupant and maker 

 thereof is a bivalve. If, however, the head of the tube be carefully examined, the 

 two tiny valves of the juvenile architect may be seen cemented into its wall. 



Famihj Pholadidae. 



Shell free, or within a tube, gaping at both ends. Thin, white, brittle, 

 edentulous, armed anteriorly with rasp-like imbrications. Hinge fitted with accessory 

 valves. Hinge plate reflected over the beaks, and furnished with a long curved 

 muscular process beneath each. Pallial sinus deep. Siphons long. The ligament 

 is strong and elastic, external, and strengthened with an accessory membrane formed 

 by the coriaceous end of the mantle, which issues betw'een the anterior ends of the 

 valves and covers it, and is, moreover, armed with siliceous granules. These shells 

 indeed exhibit the perfection of adaptation for boring mechanically into rocks, wood, 

 or other substances, and their burrows are made by constantl)' rotating tlu-ir valves 

 by means of their sucker-like foot. The animals are vividly phosphorescent, and 

 excellent eating. 



Sub-family PnOLADINiE. 

 PnoLAS, Linnaus. 

 Shell equivalve, with accessory dorsal valves. 



* ,, OBTECTA, Sow. 



* ,, INCEI, Sow. 



* ,, {Bactylina) obientalis, Gmel. 



JouANNETiA, Des Moulins. 



Shell globose, inequivalve. The front gape closed by a callous i)late. Eight 

 valve produced posteriorly, the left overlapping the dorsal valve. JJorsal plate single. 

 Umbonal processes none. 



* ,. GLOBOSA, Sow. 



* ,, Cu.MiNcn, Sow. 



