Il6 MELANDER. 



egg reveal only the usual envelopes over the embryo, /'. e., the 

 chorion, the tough vitelline membrane, the serosa with large 

 nuclei, the amnion with smaller more rounded nuclei, and the 

 blastodermhaut. The yolk of these eggs, fixed by hot water, 

 shows a definite segmentation, a dozen or so of granules being 

 aggregated about each vitellophag. 



During the next few days the embryo changes rapidly in ap- 

 pearance, due to the process of shortening, /. e., broadening. The 

 appendages lengthen, the mouth parts take on their final struc- 

 ture and position, the maxillae becoming tripartite, much like 

 Tenncs, due to the development of their palpi. The head, how- 

 ever, still continues its accelerated development, but lies free from 

 the yolk. The abdominal legs still persist, though even yet, 

 except for the terminal styles, none are formed on the " tail-piece," 

 which is more flexed than before and in which the proctodseum 

 is seen in process of formation. The serosa and amnion have 

 parted over the embryo and are drawn back as the " dorsal organ." 



The last stage of which we have material shows a marked ad- 

 vance in development, although the embryo is but three weeks 

 old. Revolution has now occurred. The envelopes, except 

 the vitelline membrane, as well as the dorsal organ, have disap- 

 peared. The embryo has grown over the yolk, but the dorsal 

 abdominal cuticle is still thin and shows its derivation from the 

 serosa by scattered nuclei over its surface. The proctodseum 

 and stomodaeum are well formed but still are separated from the 

 yolk-mass. The head-lobes have dwindled to a microcephalic 

 size, the antennas have lengthened to the base of the fore legs, 

 but even now the maxillary palpi are nearly as long ; yet the an- 

 tennal segmentation is more marked than in the corresponding 

 stage of Xiphidiuin ; the labrum is large and separate ; the eyes 

 are not yet formed. The tarsi are now suddenly flexed out- 

 ward, with the front metatarsi distinctly large. The abdomen is 

 stout and much bent on itself. The appendages, except the cerci, 

 have disappeared, and in their stead conspicuous spiracles are 

 developed. 



From the rapidity with which these stages are passed through 

 it would seem as though the embryonic life of Enibia is of short 

 duration. A development at this rate would cause hatching to 



