REPORT OF COMMISSIONERS OF INLAND FISHERIES. 139 



Figures V and II' at the right, represent, respectively, a normal 

 claw and a pair of extra claws for the purpose of illustrating the 

 significance of the relations shown in Figs. I and II. The extra pair 

 of claws (Fig. II') arise from the dorsal surface of the appendage, 

 and the arrow in each case indicates the plane of section shown in 

 the corresponding diagrams. By means of this illustration the rela- 

 tions indicated by the cross sections in the remaining figures may 

 be readily perceived. 



Specimen No. 3. (Dorsal origin of abnormal structure. See Dia- 

 gram, Fig. II.) 



A glance at the drawing for this specimen is sufficient to show that 

 the two extra dactyls and the double extra index conform almost 

 exactly with the theoretical relations for the dorsal position; the 

 three pairs of claws lie in the same plane; the extra dactyls and 

 double index are minor images of each other, and the extra dactyl 

 nearer the normal dactyl is also a minor image of the latter. While 

 comparing this specimen with the diagram it will be kept in mind, 

 of course, that the present specimen is a left chela. 



Specimen No. 4. (See diagram, Fig. V, position PPV.) 



In this specimen the abnormal parts arise from a position slightly 

 ventral of the posterior surface. Here again the actual relations 

 between the normal and abnormal claws correspond to the theoret- 

 ical schema. The morphologically anterior surfaces are in opposi- 

 tion; but they are inclined at such an angle that the toothed margins 

 are turned toward each other, while the ventral or smooth borders of 

 each claw are thrown apart. It may also be observed that here, 

 again, the extra index nearer the normal index is a mirror image of 

 the latter and belongs to the right or opposite side of the body. 



Specimen No. 5. (Origin slightly dorsal of the anterior surface. See 

 diagram, Fig. Ill, position AAD.) 



This specimen presents certain peculiar exceptions to Bateson's 



