158 MARINE AND FISHERIES 



5 GEORGE v., A, 1915 



of carapace, although there are numerous tubercles on each side, particularly 

 anteriorly. In large specimens, the fingers of the large chelipeds are relatively 

 very long, narrow and curved. The propodus or hand may be even more than 

 two-thirds as long as the body. The annulus ventralis of the female (Fig. 12, c) 

 has a very small excavation which is almost in the middle line. It is sometimes 

 on the right side (lower figure) and sometimes on the left (upper figure). This 

 recalls the dimorphism that has long been known to exist in the males and that 

 was first described by Hagen and that affects the first pair of abdominal legs. 

 Whether this dimorphism in the female is strictly comparable with that in the 

 male may be doubted. It is more like the inversio viscerum that occasionally 

 occurs in many animals. I have observed it in other species of Cambarus although 

 not in as well marked a state as in this species.* The specimens show roughly 

 about equal numbers of the two kinds. The dimorphism shown in the first ab- 

 dominal appendages of the males of this species is represented in Fig. 8, e. 



This species has a number of varieties. From western Ontario I have seen 

 only the form known as robustus (Fig. 9, e). From Iroquois in eastern Ontario, 

 I have received specimens both of robustus and of the tpyical bartonii, with a 

 square rostrum. The latter appears to mature at a much smaller size. A male, 

 23 mm. long, has the first abdominal appendages well developed and extending 

 forward between the fourth pair of thoracic legs. In a male robustus, 33 mm. long, 

 the first abdominal appendages are small and rudimentary, not extending in 

 front of the fifth thoracic legs. Hagen considered these two forms as distinct 

 species but Faxon subsequently united them into one. It is probable that further 

 study will show that they are distinct.** 



Cambarus fodiens (Cottle). Figs. 8, f; 9,d; 10,e; 11, a; 12;e. 



Astacus fodiens Cottle, 1863, p. 216. 



Cambarus argillicola Faxon, 1885, p. 76. 



This appears to be the common burrowing crayfish in Ontario. It is found 

 in swamps, etc. which become dry in the summer. At this time it retreats to 

 its burrows, the mouths of which are surmounted by the so-called 'chimneys' 

 which are formed by pellets of mud. 



Cottle records it from Ontario, but does not give the locality. A few years 

 previous to the time of publication of his article, he was residing at Woodstock. 

 Faxon records it from Toronto and Detroit. The only adult specimens I have 

 seen were given to me by Dr. E. M. Walker, who had received them from a student 

 but without any record of the locality. Strathroy (H. B. Sifton). 



Length from 60 to 70 mm. (76 mm. according to Faxon). Rostrum without 

 lateral teeth, similar to that of Cambarus bartonii robustus but without thickened 

 margins and with the tip well bent down. Carapace practically without lateral 

 spines or tubercles. Depth of carapace (except in young individuals) equal to or , 



♦Andrews (Proc. Bost. Soc. Nat. Hist., vol. 32, 1906, p. 477) found it in four out of five 

 species examined, and thinks it may be general in Cambarus. 



**Ortmann in Williamson (1907) reports the typical bartonii from near Lake St. John, 

 Quebec, as well as from Searchmont, Algoma District. 



