667 



pods proved that they were absent. This absence of the first pleopods 

 in the females of Camhariis moiitezumae had not been previously noticed 

 and raised the question whether other Mexican crayfish show this point 

 of resemblance to the American Astacus. Dr. Ortmann has been good 

 enough to examine his collection with reference to the occurrence of these 

 appendages and finds that while his specimens of C. montexiimae lack 

 the first female pleopods, specimens of the other two sub-genera of the 

 Mexican and Central American regions do not lack them. The appen- 

 dages are found in 5 other species, of the subgenus Cambarus, in 10 

 of the sub-genus Faxonius, in 9 of the sub-genus Bartoiiius, which he 

 has examined; and probably a further search will but strengthen the 

 common belief that these appendages are generally present throughout 

 the genus Cambarus. Strange to state, however. Dr. Ortmann finds 

 these appendages absent in his one sj)ecimen of C. pelluciduSy from In- 

 diana. 



The facts regarding the first abdominal somite and its appendages 

 in crayfishes seem to be as follows: In all crayfishes in the Southern 

 Hemisphere the appendages are absent in both males and females, as far 

 as is known: In all crayfishes in the Northern Hemisphere the appen- 

 dages are present in the males, and used as necessary reproductive organs, 

 and are present as small and apparently almost useless organs in the fe- 

 males in most crayfishes of America, Asia and Europe. They are absent 

 in the following few cases : In the crayfishes of eastern Asia; western coast 

 of America; in the Mexican form, Cambarus montezumae; in the blind 

 cave form, C. pellucidus, of Kentucky and Indiana and also, according 

 to Huxley in some specimens of an English crayfish, though other spe- 

 cimens have the appendages present and some have only one. In our 

 present understanding of the history of the crayfishes we can only con- 

 clude that these appendages have been independently lost in all of the 

 above cases of crayfishes in the northern hemisphere, but further know- 

 ledge of the crayfishes of the southern hemisphere may put the matter 

 in a different light. 



In these boiled and preserved specimens, young were still fastened 

 to the pleopods of the female in two cases, 16 in one and 30 in the other. 

 All these young were alike and were fastened by their large claws, which 

 were much recurved so that the young could not be easily detached. 



The young were 3 I/2 mm long and still well supplied with yolk 

 though not so obese as is the case with the recently hatched young of 

 C. a f finis and C. clarkli. The eyes were very heavily pigmented and 

 long, while the rostrum was not much bent down though rather blunt 

 and without the lateral spines, which, however, as well as a more mu- 

 crinate tip, were already formed within the exoskeleton, to be set free 



44* 



