No. 405.]  NORTH-AMERICAN INVERTEBRATES. 749 
the nettling filaments, or acontia, already mentioned. The line 
of attachment of a mesentery to the column wall is often 
marked, as in the Edwardsiz (Fig. 1), by a depressed line or 
furrow on the exterior of the column. 
A second internal feature of importance is the sphincter, or 
circular muscle, in the region between the oral disk and the 
column. This muscle, by virtue of which the upper part of the 
column may be puckered over the oral disk when this is con- 
tracted, lies either in the intermediate layer of the body wall 
(mesogloea), as in the Paractida, or in the inner layer (endo- 
derm), as in the Bunodida. These distinctions are not easily 
made out unless the region in question is examined microscopi- 
cally. When the sphincter is poorly developed, as in the Bolo- 
ceridæ, the polyps, even when contracted, usually leave their 
tentacles exposed. 
The following key gives the species of Actiniaria recorded 
for North America at depths within 100 fathoms of the sur- 
face and occurring north of Florida on the east coast, and north 
of southern California on the west coast. In indicating the 
geographical range the following abbreviations have been used : 
N., Arctic Ocean to Cape Cod. A., Arctic Ocean to Puget Sound. 
M., Cape Cod to Cape Hatteras. P., Puget Sound to San Francisco 
S., Cape Hatteras to Florida. D., San Francisco to Southern California. 
KEY TO THE TRIBES OF THE SUBORDER ACTINIARIA. 
— 
- Colonial . à T : : : . * Zoanthez 58 
- Not colonial 2 
Tentacles in. two ile one nein (principal) wad the het cir- 
cumoral (accessory) . ; . Cerianthee 56 
N = 
2. Tentacles in a single circle 3 
3- Column smooth, wrinkled, or vit longitudinal ionia, at eu twelve 
in number (six pairs of mesenteries) . Hexactinie 7 
3. Column with eight longitudinal furrows (eight TER 
Edwardsiæ 4 
GENERA AND SPECIES OF EDWARDSIÆ. 
4. Tentacles sixteen or fewer ‘ Edwardsia 5 
- 
Tentacles more than sixteen, usually at Haast tiet PS Edwardsiella 6 
Polyp slender ; tentacles sixteen ; non-parasitic 
Edwardsia elegans Ver., N., low water 
bn 
