Development of Estheria Packardi. 17 



at some distance below the eye, is very conspicuous, and 

 exhibits much the same appearance as in the larval stages. 



The antennulæ, issuing from the ventral face of the head in 

 front of the labrum, are well denned, though still rather short 

 and claviform in shape, without any trace of segmentation 

 or lateral lobules. 



The antennæ exhibit a structure somewhat intermediate 

 between that in the larvæ, and that characteristic of the 

 adult animal. As in the latter, the scape is bent anteriorly, 

 exhibiting an almost elbow-shaped flexure at the base, and 

 from this flexure the above-mentioned rudiment of the 

 masticatory process is seen to issue. At the end the scape 

 exhibits several imperfectly defined joints, not found in the 

 larva, and from the anterior side of them several small, 

 spine-like bristles are seen growing forth. Posteriorly a 

 single, rather short, ciliated bristle occurs, which is easily 

 recognized as the remnant of the strong, falcate seta origin- 

 ating from the same place in the larva. This bristle be- 

 comes subsequently lost altogether, as also the basal pro- 

 cess, which latter becomes replaced by a bundle of ciliated 

 setæ. The rami are still rather short, though some- 

 what more fully developed than in the larva. The outer 

 ramus is the larger, and is divided into 5 or 6 articula- 

 tions, the 2 middle of which have each anteriorly a single 

 short spine. The last articulation has a similar spine and 2 

 ciliated setæ, and each of the 3 preceding articulations a 

 somewhat longer seta posteriorly. The number of natatory 

 setæ on this ramus is accordingly the very same as in the 

 larva. The inner ramus has retained its original simple 

 cylihdric form, though a slight trace of segmentation is visible 

 in the middle; and it carries only 3 apical setæ, the 4th seta 



