CHELYMORPHA ARGUS. 37 



form in the spindle (figs. 47-49). One is ring-shaped, the ring being 

 formed by union of the free ends of the segment so that the spindle 

 fibers are attached to the middle of each univalent chromosome (fig. 

 49). This method of ring formation, like that described by Mont- 

 gomery ('03) for the Amphibia, is of very frequent occurrence in the 

 spermatocytes of the Coleoptera. The dumb-bells are so bent at the 

 ends (fig. 52J that the spindle fibers, here also, are attached at or 

 near the center of each univalent component of a bivalent chromo- 

 some, and the separated, univalent chromosomes go to the poles of the 

 spindle in the form of Vs. As in Tenebrio the heterochromosome pair 

 is late about coming into the equatorial plate (figs. 47-48), but it does 

 finally take its position with the others (fig. 49) and separates into 

 its component parts somewhat earlier than the other, bivalents 

 (figs. 52, 53). Figures 50 and 51 show polar views of the metaphase, 

 the smaller element (x) being the unequal pair. The chromosomes 

 in late anaphase are too much crowded to give clear drawings. As 

 in all the beetles so far studied there is no rest stage between the two 

 maturation divisions, but the late anaphase of the first mitosis passes 

 over quickly into the second spindle. Figures 54 and 55 are typical 

 equatorial plates of the second division, one showing the small chro- 

 mosome (5), the other its mate more nearly spherical than the others 

 (/). An anaphase including the small chromosome is shown in figure 

 56. As in the species previously described the spermatozoa are evi- 

 dently dimorphic. 



Female somatic equatorial plates from egg follicles are shown in 

 figures 34 and 35 ; 22 chromosomes are present and no one is without 

 an equal mate. 



Odontota dorsalis (Family Chrysomelidae). 



Odo7itota dorsalis \s a small leaf-beetle found on Robinia pseudacacia. 

 The chromosomes are comparatively few in number, 16 in the sperma- 

 togonia (figs. 58 and 59), and of immense size when one considers the 

 smallness of the beetle. In some of the spermatogonial cysts many of 

 the chromosomes are V-shaped as in figure 58, while in others all, with 

 the exception of the small one, are rod-shaped as in figure 59, which 

 looks like a hemipteran equatorial plate. The spermatogonial resting 

 nucleus (fig. 60) contains a large plasmosome (/>), but no condensed 

 chromatin. The synizesis and synapsis stages are similar to those 

 in Chelymorpha (figs. 61 and 62). The spireme stage (figs. 63, 64) 

 contains, in addition to the pale spireme, a very conspicuous group 

 consisting of a large plasmosome with a large and a small chromo- 

 some attached to it. In the prophase, before the nuclear membrane 

 has disappeared, this group is easily distinguished from the other 



