28 
Dwelling-cavity lined with a shelly tube . Siphons with 
lateral palettes . Teredina. 
7. Teredo. 
Shelly valve distinct. Palettes simple, broad. 
1. T. , t. 349. f. 3. 
2. T. navalis, t. 349. f. 4 . 
3. T. norvegica (fig. 10). 
Fig. 10 .— Teredo norvegica. 
a be 
a, small shell, b, elongate body with, c, siphonal palettes. 
8. Furcella. 
Shelly valves none. Palette simple, broad. 
1. F. polythalamia. Gray, P. Z. S. 1857. 
9. Xylotrya. 
Shelly valves perfect. Palettes elongate, cylindrical, articulated. 
B. Cartilage marginal, under the ligament. 
Fam. 2. Gastrochcenidoe. 
Foot small, cylindrical, anterior, not byssiferous. Gills two on 
each side. Shell gaping in front. Cartilage small, weak, mar- 
ginal. Living enclosed or imbedded in a shelly case. 
a. Valves both soldered into the shelly sheath, the umbones alone 
visible externally. 
1. Penicillus. 
1. P. vaginiferus, t. 341. f. 2. 
b. Valves regular j one free, the other forming part of the very 
irregular shelly sheath. 
2. Bryopa. 
1. B. aperta, t. 340. f. 6, 7, 8. 
2. B. melitensis, t. 340. f. 3, 4, 5, 9, t. 341. f. 1. 
3. B. , t. 338. f. 1. 
c. Valves regular , equal, free in the shelly sheath. 
3. Ch/ENA. 
1. C. faba, t. 339. f. 2, 3, 4, t. 347. f. 6, 8. 
