4i8 



DISCOVERY REPORTS 



It is a matter of great difficulty to determine how many stages there may be in the 

 development oi Josus, since apart from stage I Gilchrist obtained only a single specimen 

 (of 3-8 mm.) of another early stage. Von Bonde (1932) did not add to our knowledge of 

 this species. The Discovery material consists of about fifty specimens all much older 

 than this specimen of Gilchrist's. Taking as a basis specimens of four distinguishable 

 stages from St. 85, it is found that these increase in size by a growth factor of about 1-3, 



Fig. 25. Panulivus D, 57 mm. St. 1554. 



whether total length is taken or pre- or. post-labral length, showing that in these parti- 

 cular stages (from 10-4 to 2275 mm.) irrere is no appreciable differential rate of growth. 

 The fifty specimens measured fall into six groups of which the average sizes are : 



