494 GEOLOGICAL SURVEY OF THE TERRITORIES. 



capacity of the water, but especially in autumn, it exceeds by far the 

 beginning of the eighth abdominal segment. Likewise this part is 

 longer in old individuals than in poiing^ otherwise sexually mature speci- 

 mens. If we examine, relative to this, specimens on the extreme concen- 

 tration-limits of the salt water, we find a great difference amongst them. 

 In A. milhaiisenii the stomach part of the tract scarcely reaches to the 

 beginning of the sixth apodous segment, but in our species of Branchi- 

 pus this part terminates not far from the anal orifice. 



Finally, we must mention as a character of our A. salina the following : 

 The claspers, or the lower antennae in the males, are much broadened 

 on their second joint, having such a form as the male claspers of A. ari- 

 etina, according to a drawing of S. Fischer.^ 



On the anterior part of the male claspers, between the head and the 

 protuberances, serving to clasp the female with, near the bent-down 

 margin, there are two groups of ten-pin-shaped teeth or spines, in one 

 group on each side. It appears that these denticulate groups corre- 

 spond as rudiments of the well-known appendages, occurring on the 

 claspers of many species of Branchipus, as for instance in BrancJiipus 

 spinosns. Such bundles of teeth or spines occur also in that form of 

 Artemia examined by Ulianin from Sebastopoiis, and which was re- 

 garded by him as a race of Branchipus arietinus Grube ( = variety of 

 A-) t. arietina Fischer). 



Artemia salina Milne-Edw. varietas a. — This form, called by me Arte- 

 mia salina var. a., approaches the species Artemia salina so much that, 

 beside its larger size, no other distinct characters exist by which we, with 

 the general variability of so many characteristic points of the Artemi£e 

 of this species, could distinguish the same. However, if we have speci- 

 mens before our eyes of this or that form, we must confess that we have 

 to do with forms differing so much that we even could regard them as 

 diflerent species of the genus Artemia. 



A view of profound truth has been expressed already in 1871, by 

 Professor C. Th. A^on Siebold, on the comparison of descriptions of Ar- 

 temia salina ot various authors. Siebold says •? " In comparing the vari- 

 ous descrijjtions and illustrations given of Artemia salina., we become 

 convinced that probably with this species-name entirely different species 

 or races were marked out, and therefore a revision of the species of the 

 genus Artemia by carci nolo gists would be recommendable, though this, 

 however, would necessitate a comparison of vast material, especially as 

 the hitherto insufficient diagnoses of the species of Artemise, without 

 reference to the characteristic formation of the male heads, have been 

 compiled." Further on Professor Siebold, in perusing the descriptions 

 of the second antennae of the males in Artemia salina and that of the 

 ])ostabdomen of this species, foresaw what is now actuallj^ corrobo- 

 rated. I find two principal races of Artemia salina, one of which is of 

 smaller size, the Artemia salina, but the other is Artemia salina varietas 

 a., and there are, besides, still other changes of its generations depend- 

 ing on various concentrations of the salt water, including also those 

 degraded and modified generations of the tico races of Artemia salina, 

 wliich are, as I suppose, recorded in zoological literature under the name 

 of the species of Artemia milhausenii. 



The main distinctions of the variety a. of the species Art. salina 

 forms another mean length of it. Accepting as the mean length of 

 Artemia salina six lines, we must accept eight lines of French foot for 



' Middendorf's sibirische Reise. St. Petersburg, 1851, Vol. II, 1st part. Table VII, 

 fig. 32. 

 2 " Beitriige zur Parthenogenesis der Arthropoden." Leipzig, 1871, p. 203. 



