6 



were scattered promiscuously, one or two on the bottom and a 

 few as far as half way to the top of the jar. The animals also 

 appeared to prefer the solid walls of the jar to the microscope 

 slides, in most cases managing to find a passageway between two 

 slides and depositing the egg-case on the jar. Fifty egg-cases 

 were counted and others were undoubtedly overlooked. Since 

 these cases are normally 2.5 mm. in diameter by 1 mm. high, 

 while an average parent is but 7 mm. in length, by 4 mm. in width, 

 and 2.5 mm. high, the average of at least seven egg-cases to every 

 individual is surprisingly large. It is possible that' not all of the 

 seven individuals deposited eggs, in which event the average 

 number per specimen would be greatly increased. The egg-case 

 (Plate 2, fig. 2) consists of a hollow, hemispherical, transparent, 

 gelatinous, enveloping layer. It is approximately 0.1 mm. in 

 thickness where fastened to the jar. A thin film of the same 

 material prevents the contents of the case from coming in contact 

 with the object upon which it is deposited. Within are normally 

 seven capsules, apparently quite separated from the outer case by 

 an extremely transparent, jelly-like medium. This is clearly 

 shown when the outer case is injured so that infusoria and other 

 minute animals are allowed to gain entrance to but one of the 

 capsules. The egg and contents of this capsule are then soon 

 devoured, but continuous probing for days by myriads of the 

 small animals fails to reveal any passage for the most minute, 

 between the capsules and the outer casing, or from the injured 

 capsule into the uninjured adjoining one, for the eggs within the 

 uninjured capsules continue to develop normally. Each capsule 

 within the case possesses its own complete, transparent, envelop- 

 ing wall, is filled with a transparent, colorless, viscous liquid, and 

 contains a single egg. The first egg-cases to appear all contained 

 seven capsules with the exception of one containing nine and one 

 with eight. These two exceptions were otherwise normal, the 

 eggs developed, and the embryos all lived to escape from the case. 

 Those egg-cases which appeared later contained fewer capsules, 

 until, after several days had passed, the few egg-cases laid con- 

 tained but one capsule each. These single-capsuled cases were 

 likewise normal in other respects, for as large a percentage of the 

 young left the egg-case in apparently healthy condition as in the 

 seven-capsuled cases. It appears that the egg-laying season of 

 this species is of short duration. Thirty-five specimens collected 

 on May 7, and kept under conditions as nearly similar as possible 

 to those of the first lot, deposited less than thirty-five egg-cases, 



