370 University of California Publications in Zoology. [Vol.4 



before the process. The first individual listed presents approxi- 

 mately normal conditions and has an antapieal ratio of 1.2. With 

 two exceptions in the table the ratios after aiitotomy lie between 

 1 and 1.3 or including the two cases of short left horns, between 

 0.9 and 1.3. The two exceptions both have disproportionately 

 long left horns, that is the right horn has undergone autotomy 

 while the left retains its primitive length. 



In the main the data from C. inflexum support the view that 

 both autotomy and regeneration are regulatory in this species. 

 The exceptions are such as might attend schizogony or slight de- 

 partures from coincident autotomy of the horns. 



The data from C. intermedium are of similar import though 

 somewhat more aberrant. In the thirteen instances there are 

 five (5, 7, 8, 9 and 10) marked cases of disproportionate horns, 

 that is of non-regulatory or possibly partially completed auto- 

 tomy. One of these (9) has already two section planes at 2.8 

 transdiameters which when completed would bring the antapieal 

 ratio to 1.3, approximately the norm of the species. The re- 

 maining eight cases present antapieal ratios, after autotomy 

 ranging from 1 to 1.3. 



In ten individuals of C. longipes there occurred seven in- 

 stances of autotomy, all of which leave antapieal ratios which 

 fall within the limits 1.0 and 1.4, and five of them within 1.0 

 and 1.2. Similar regulatory relations in autotomy of the an- 

 tapicals exist in the single individuals of C carriense and C. 

 arcuatum' which are recorded in the table. 



In C. biceps the right horn is always relatively very small 

 and plays but little part in the mass relations and form resist- 

 ance which control orientation and locomotion. Its autotomy 

 and regeneration are, however, of frequent occurrence but are, it 

 seems, often independent of these processes in the other horns. 

 Autotomy of this horn is very frequent, much more so than that 

 of the other horns. In many collections most of the individuals 

 of this species will have the right horn truncated, as though there 

 had been autotomy and subsequent healing without regenerative 

 extension to the slender tapering antapex of typical form. Nor- 

 mal regeneration is, however, occasionally seen. As in other 

 species so also in C. biceps there is a correlation in the autotomy 



