Miscellaneous. 415 



animal seizes the penis of the male between its cirri and driigs it 

 inside its valves, where it retains it, unless the latter, as is often the 

 case, penetrates thitlier by itself. The animals remain in this way, 

 pressed one against the other, producing little movements of con- 

 traction. Emission takes place, and the sperm is always deposited, 

 in the form of a gelatinous mass, beneath the ovigerous frenum on 

 each side of the body. On each occasion that I noticed it it was 

 the smaller animal of the two that plfiyed the part of the male. 



If there are several specimens of Li'iias or Balanus whose sperma- 

 tozoa are ri])o surrounding another individual which is ready to be 

 fertilized, it is not unusual to see several of them participating in 

 the fertilization of the same individual. 



Another phenomenon is frequently witnessed which is strange 

 enough to be worthy of mention. Two Balani {B. tintinnahidum) 

 are attached to the same fragment of rock, both of small size, and 

 both with the cirri extended in the same direction. The hinder- 

 most one wishes to fertilize its neighbour : it tries, but its penis is 

 too short and cannot reach as far as the orifice of the chamber in 

 order to deposit its sperm there. Then, by a simple process which 

 might be termed ingenious, it turns abruptly in its chamber about 

 three quarters round, and thus diminishing the space which sepa- 

 rates them by the length of the orifice of the chamber, it is able to 

 succeed in fertilizing its neighbour. 



From these facts, and others which cannot find a place in this 

 note, we must conclude that the ordinary mode of fertilization in 

 the Cirrhipedes is reciprocal. When this method is rendered 

 impossible, by various circumstances, more especially by the fixation 

 of the animals, self-fertilization may also take place. 



There is no actual copulation, but merely approximation of the 

 sexes and deposition of fertilizing matter in the neighbourhood of 

 the oviferous females. 



It was impossible to determine the existence of reciprocal fertili- 

 zation in PoUicipes : I am inclined to believe that in this case there 

 is only simple self-fertilization. — Comptes liendus, t. cxiii. no. 20 

 (Nov. 16, 1891), pp. 706-708. 



On the Embryogemj of Sagitta. By M. S. JorRDiiJT. 



Observations made on the development of Sagitta have led me to 

 differ from Kowalewsky and Biitschli in my conception of the 

 formation of the archenteric cavity, which appears in these animals 

 at the ijastrula stage. According to the naturalists mentioned, this 

 cavity, which is simple at first, should di\-ide at its anterior region 

 into three lobes, while preserving its simplicity in its posterior 

 portion. The lateral lobes of the tripartite region would constitute 

 the general body-cavity : the median lobe would form the digestive 

 canal of the perfect animal. This view appears to me to be 

 erroneous. 



The archenteric cavity, open behind at the blastopore, which 

 occupies the region of the future anus, gives rise not to the general 



