Miscellaneous. 375 
cycles (10, 10, 20, 40, 80) on the coasts of Normandy, and only 
four cycles (10, 10, 20, 40) on the English coasts*; but I attach 
little importance to this fact. 
As to the number of tentacles in each cycle, it deserves careful 
examination ; if anomalies exist, if certain individuals escape from 
all rule, it is none the less evident that one may point out archetypes 
for the greater number of species. 
1. The type with 6 tentacles and its multiples (12, 24, 48, &c.) is 
the commonest; it is this that has induced some observers to sup- 
pose that all the Actinize were derived from it. From the obser- 
vations of Mr. Gosse, and from my own, this type exists in about 
twenty Actiniz of the European seas. The Bunodes, among others, 
may be considered as perfect Hexactinie. 
2. The type with 8, and multiples of 8, tentacles is very frequent. 
It is indicated for nine species, to which, probably, the Cerianthi 
may be added. 
3. The type with 10 tentacles is only seen in Teaha felinat. 
4, Palythou sulcata alone has 11 tentacles. 
5. These various types combine among themselves; thus the for- 
mula of Edwardsia carnea would be 8, 8, 12, and that of Corynactis 
viridis 16, 24, 32, 32. 
6. Lastly, there exist indeterminate types; must we refer to type 
6, 12, &e., or to a type 9, 18, and its multiples, the two following 
species—Anemonia sulcata (36, 36, 36, 72) and Ilyanthus Mitchelli 
(18,18)? What is the type of Auwreliania angusta, of which the 
marginal series is composed of 42 tentacles? Palythoa Couchi has, 
according to my observations, 2 cycles of 14-15 tentacles. Mr. 
Gosse attributes to it 24 tentacles (12, 12) in the young, and 28 
(14, 14) in the adults, which would prove that at one time this 
species 1s a Hexactinia. 
These facts make one think that, in the zoological group of the 
Actiniz, the number of tentacles has not the value that has been 
attributed to it. The type has not even the importance of a generic 
character, since in the genera Sagartia, Phellia, Haleampa, and 
Edwardsia certain species have 8, and others 12 tentacles and their 
multiples, 
The variability of the number of tentacles is explained by the 
embryogeny of the Actinic, the embryo having successively 4, 6, 8, 
10, and 12 dissepiments and tentacles. By assuring an arrest of 
development at each of these periods, we obtain the various types 
which correspond to them; and in certain species the normal com- 
bination of the two types (Hdwardsia carnea and Corynactis viridis) 
faithfully represents the normal development of a Hexactinia, which 
passes from 8 to 12 dissepiments and tentacles. Seeing how much 
the tentacular type varies in the Actinie, one may also doubt the 
importance of the number of systems and cycles in the Corals. 
* In the same way Sagartia sphyrodeta has 5 cycles (8, 8, 16, 32, 64) 
on our coasts, and 4 cycles in England (8, 8, 16, 16), according to Gosse. 
+ L. Agassiz has discovered in America a species (Jthodactinia Devisit) 
of the same type. Its embryos have 10 tentacles only. 
