480 MEMOIRS OF THE CARNEGIE MUSEUM 



that the nice restriction of certain periods in the seasonal history is primarily due to 

 differences of temperature. It is only natural that an equalizing of the temperature 

 must tend to efface the seasonal periods. 



4. Camba ms diogenes. 



According to my observations, which extend over the period from March 22 to 

 November 17, this species also agrees in the main features of its seasonal develop- 

 ment with C. obsctirus. 



I have the following records for females with eggs: April 5, 1905 ; April 19, 

 1905; May 2, 1901; May 14, 1899, (collected by Atkinson, Graf, and Williamson) ; 

 May 21, 1906 ; May 22, 1905 ; May 27, 1904. On May 21, 1906, and June 2, 1905, 

 I found several females with newly hatched young under the abdomen. In no 

 other part of the year has this been observed, and thus the spawning and hatching 

 season is well fixed (April, May, and the beginning of June), and is found to be 

 identical with that of C. obscurus. 



The number of eggs is considerably less than in the case of C. obscurus, and 

 generally falls considerably short of one hundred. The spawning does not take 

 place outside of the burrows, but inside of them, and this was most evident in a 

 female collected on April 6, 1905, (Renfrew, Butler County), in which the eggs were 

 quite fresh, witli traces of the "apron " still visible. This female was dug out of its 

 hole, as were all the rest with eggs or young ones. 



After hatching the young remain a short time under the abdomen of the mother. 

 But soon they leave her, yet remain in the same hole. I have repeatedly foUnd 

 young specimens in the same hole with their mother, namely, on June 13, 1904 ; 

 June 15, 1905; July 6, 1905; July 19, 1905. The smallest were about 10 mm. 

 long. These young specimens generally occupy a separate part of the burrow, and 

 are often found near to and inside of the mouth of a closed chinmey. They remain 

 in the hole until they attain a length of 20 mm., which happens toward the end of 

 July. Then they leave the hole of the parent crawfish and begin to build their own 

 little holes and chimneys. I observed this on July 26, 1904, at Derry, Westmore- 

 land County, when I discovered a female 20.5 mm. long in a small hole of its own. 

 At the same date I found a larger one, 30.5 mm. long, which may have belonged to 

 the same generation. On August 4, 1901, at Francis Mine, near Burgettstown, 

 Washington (Jounty, I found numerous young specimens between 20 and 29.5 mm. 

 long, all in their own holes. On August 22, 1905, at Squaw Run, Allegheny County, 

 I discovered two young specimens 22 and 28 mm. long. On August 26, 1905, at 

 Baden, Beaver County, specimens 31.5 to 42 mm. long were found apparently under 



