52 PROCEEDINGS OF THE NATIONAL MUSEUM vol. m 



in a greater state of attenuation than my formalin specimens. In 

 order to obtain some idea of the differences the length-width relation- 

 ship may be expressed in the form of an index (w/lXlOO). Mean 

 values for the Pelham population ranging from juvenile to mature are 

 6.2, 6.2, 5.8, and 6.0. If the longest worm is correlated with the great- 

 est diameter and the shortest with the smallest the following indices 



* A A* A*«« AS 



a a» » •.y^a • • • • 



o •© •• o 



fo o o o 



I M * • 



'^o o o 



HATURC 

 SCUI-HATURE 

 IHMtTURE 

 JUVCNILE 



Figure 1. — Relation of length to diameter in specimens of Pheretima hupeiensis preserved 



in 4 percent formalin. 



are obtained for the Asiatic specimens: Chen 4.3-4.6, Kobayashi 3.3. 

 These forms appear more slender than the Pelham stock, 



Avel (1929) has shown that size variation in Allolobophora is de- 

 pendent on nutrition, and Pickford (1937) says that because of this 

 factor it would be impossible to indicate a size range for a species that 

 would have taxonomic significance. This is further substantiated by 

 the apparent larger size of the oriental population of P. hupeiensis. 



Weight: A group of 162 worms collected from the nursery plot at 

 Pelham on Aug. 22, 1952, were classified into the four categories of 

 maturity and weighed. The range was from 898 mg. for a mature 

 worm to 41 mg. for a juvenile. The means and their standard devia- 

 tions are listed in table 1. The mean value for juveniles is 103 mg., 

 with no weights above 223 mg. being recorded for this category. It is 

 probable that somewhere between these values the majority of the 

 population will develop prominent male papillae. The figures for 



