Miscelluneous. 257 



the specific characters of A. Miihlhausenii. The author minutely 

 describes the gradual changes that he observed. These were mani- 

 fested especially in the caudal part, and were accompanied by a 

 diminution of size. 



These observations, made upon animals living at freedom in salt 

 marshes, are corroborated by experiments made by the author upon 

 Artemice reared in captivity in water of which the saltness was 

 gradually increased. Under these conditions he observed the same 

 transformations leading to the same forms. 



The inverse experiment was tried with Artemia MuMhausenii 

 taken in the salt marshes and reared in water rendered less and 

 less salt. This Artemia was then seen to retrograde by degrees 

 towards the fovm of Artemia salina. 



In proportion as the saltness increases or diminishes a correlative 

 increase or diminution of the surface of the branchiae is observed in 

 the Artemice. The form of these organs also differs in the two 

 species ; those of Artemia salina are of an elongated form, their 

 two dimensions being in the proportion of one to two, whilst those 

 of A. Miildhanseini are oval, and their two dimensions are in the 

 proportion of two to three. 



According to M. Schmankewitsch, the only(?) anatomical cha- 

 racter that distinguishes the genus Brancliipvs from Artemia is that 

 in the latter we count (including the two segments which bear the 

 external sexual organs) eight apodal terminal segments, the last of 

 which is nearly twice as long as the preceding one ; whilst in Bran- 

 chipvs there are nine apodal segments, the last two of which differ 

 but Kttle from each other in length. When a series of generations 

 of Artemia have been reared in water less and less salt, the last 

 segment (8th) divides into two, when there are nine apodal seg- 

 ments as in Braiichiptis. Moreover it must be noted that in youth, 

 at the moment when they have just quitted the larval state, the 

 Brancltipodes have only eight apodal abdominal segments, the last 

 of which has the same proportions as in Artemia. 



It is not only by the number of abdominal segments that the 

 Artemia} approach Branchipus under the influence of the surround- 

 ing medium ; other characters which the former genus borrows 

 from the second also make their appearance ; this is the case, for 

 example, with the length of the caudal lobes, the number of setse 

 they bear, &c. 



The results of these observations lead the author to the conclusion 

 tluit the Artemiic. which ordinarily i)ass their lives in strong salt 

 water are merely degraded forms of Branchijiudes, produced under 

 the influonce of the surrounding medium. Inversely we may sup- 

 j)0se that the Branchipodcs represent a form more advanced in deve- 

 lopment than the Artemice. 



The facts contained in M. Hchmankewitsch's memoir appear to be 

 well observed, and possess great interest from the point of view of 

 the theory of transformism. We cannot, liowcver, abstain here 

 from making one or two critical remarks : — first, tliat the author 

 makes no allusion to a rather important character which separates 



