John P. Munson 313 



depressed, not keeled ; toes strong, broadly webbed ; carapace dark green ; 

 plates of carapace in quincunx, and margined with paler brown below; 

 concentric striation of cestal plates visible but not strongly marked; 

 marginal plates not united in the adult, apparently so in the young; 

 adjacent edges of posterior marginal plates forming a compound curve; 

 marginal plates slightly notched in front; marginal plates twelve, with 

 two narrow supernumerary in front; anterior and posterior marginal 

 plates divided by vertical, yellowish stripe; lateral plates with sligbtly 

 reticulate, yellowish markings. Head small, hind legs clubshaped, larger 

 than forelegs ; four toes of hind feet with long claws, five claws in front. 

 Marginal plates ornamented below with conspicuous, bright red lines; 

 feet and tail black, striped with yellow; head and neck green, covered 

 with smooth skin; side of head and neck marked with yellow stripes 

 converging in front of the eye, and crossing the iris. Plastron red or 

 pink, and marked with a bilaterally symmetrical design of brown, which 

 is very characteristic both in the younger and in the older forms. 



Methods. — Preserving fluid, picro-nitric ; dehydrated in 15-100 per 

 cent alcohol, passed through chloroform and imbedded in paraffine; sec- 

 tioned five fi, and stained on the slide. The following stains have been 

 used, and have been found useful about in the order named : saffranin, 

 acid fuchsin, Delafield's haematoxylin, picro-carmine, eosin, l)orax car- 

 mine, ammonia carmine, orange G., Bismark brown, Vesuvin brown, 

 violet blue, dahlia violet, iodine green, Congo red, anilin blue, anilin 

 red. Many of these stains were also variously combined. Thus: ITrenia- 

 toxylin and picric acid; hematoxylin and eosin or acid fuchsin, liaema- 

 toxylin and saffranin, etc. I have also found it profitable to study the 

 Qgg in the living state or merely hardened and killed without imbedding 

 or sectioning. Iodine applied to eggs in this condition under tlie cover- 

 glass gives valuable and interesting results. It is surprising that iodine, 

 which has been found so valuable in the study of living plant tissue, has 

 not been more extensively used in the cytology of animals, 



THE OVARY. 



On removing the plastron of the adult animal, at the proper season of 

 the year, after the first of May, the ovary, with its numerous largo, yellow 

 eggs, is the most conspicuous internal organ exposed. It lies in the 

 abdominal cavity, and when the eggs are grown, or nearly so, fills the 

 abdominal cavity between the hip girdle and the shoulder girdle. One 

 such ovary contains, besides fifteen or twenty comparatively large spheri- 

 cal eggs, measuring three-fourtlis of an inch or so in diameter, and hav- 

 ing a deep yellow coloration, many stages of the growing eggs down to 



