36 CONCHOLOGY. 
at the posterior extremity. Inhabits the Indian seas. Four 
species. i 
Fistulana clava. Fistulana gregata. 
F. corniformis. F. lagenula. 
4. Genus Septaria. Pl. VI. 
Animal. Unknown. 
Shell. A very long testaceous tube, gradually attenuated to its 
upper end, and divided internally by vaulted divisions seldom 
complete, the extremity of which is terminated by two slender 
tubes without interior partitions. Specimens of this genus have 
been found five feet long. Found in sand on the shores of the 
Indian seas. ‘Two species. 
Septaria arenaria. Septaria maculata. 
5. Genus Teredina. Pl. VI. 
A fossil genus; consisting of a testaceous cylindrical sheath, 
the posterior extremity closed, and exhibiting the two valves 
of the shell it encloses; the anterior end open. T'wo fossil 
species. 
6. Genus Teredo. PI. VI. 
Amimal. Body very much elongated, vermiform: mantle very - 
fme, tubular, opening only at front and below for the issue of a 
teat-shaped foot ; mouth small ; very short, distinct tubes ; the in- 
ferior or respiratory one somewhat larger than the superior ; labial 
appendages short and striated; branchie very long, narrow, 
united, and prolonged throughout the extent of the tubular cavity 
of the mantle; only one large contractile muscle between the 
valves ; at the point of junction of the mantle and tubes is a mus- 
cular ring, in which is implanted a pair of corneo-calcareous ap- 
pendages. 
Shell. Thick, solid, very short or annular, open before and 
behind; valves equal, equilateral, angular and trenchant before, 
only touching each other by the opposite edges ; no hinge ; a con. 
siderable spoon-like cavity ; only one feeble muscular impression. 
