218 



J. H. ORTON. 



continued anteriorly as the main gonoduct (see Fig. 2, p. 214). The 

 largest individual tubes in a very fine specimen were found to be about 

 3-0 cm. long, and less than 1 mm. wide. 



The number of tubes was counted for the purpose of comparison with 

 those in C. saxicola in 6 individuals, of which 3 were males and 3 females. 

 In these specimens, whose lengths were (1) 5-3, (2) 7-2, (3) 8-2, (4) 8-6, 

 (5) 9-0, and (6) 12-5 cms., there were respectively 528, 582, 473, 513, 839,* 

 and 250 tubes. A similar large number of tubes was, however, observed 

 in all the specimens obtainable, namely, 30, of sizes similar to those given 

 in Table 1. A comparison with similar specimens of C. saxicola from 



Fig. 4. — External view of the calcareous collar of C. saxicola drawn from a glycerine 

 preparation after separating the ventral piece from the adjacent right radial piece 

 (X '^). 



Table 2 indicates at once the great difference in this respect between 

 the two species. The number in the specimen drawn for Fig. 2 was not 

 counted. In this figure it may be mentioned that the tubes shown are 

 chiefly those constituting the upper of several similar layers. 



It is an interesting fact that the examination of the gonad of even 

 these few specimens of C. normani indicates a similar range of variation 

 to that observed in C. saxicola, namely, that the males (numbers 1, 2, 

 and 5) possess more gonadial tubes than the females (numbers 3, 4, and 6), 

 that the number of these tubes is not necessarily larger in the larger 

 individuals, and that within the species there is a wide range of variation 

 in the number of the gonadial tubes, which may vary from about 250 

 to more than 800. 



* At least this number were present. Tliirty-nine tubes which might have been broken 

 were not added to the total. 



