
922 The American Naturalist. [October, 
and it furnishes a strong argument in favor of the view that the larva is 
ancestral, 
Mr. Field published a contribution to the Embryology of 
Asterias. In this form the mesenchyme formation precedes and 
is continued during the process of invagination, confirming the view of 
etschnikoff and Korchelt as to the absence of two “‘ urmesenchyme- 
zellen’’in the Echinoderms. The author agrees with Semon’s recent 
paper on the formation of the adoral band. At the apex of the 
preoral lobe there is an ectodermic thickening comparable with the 
apical plate of Tornaria and Trochophore. The formation of a right 
water pore is described in detail, confirming Prof. Brooks’s discovery 
and reaching the same conclusion that ‘‘ the state with two bilaterally 
symmetrical water pores is a definite stage in the ontogeny of 
Asterias, and that it has a phylogenetic significance. The view 
that the bilateral larval form of the Echinoderms is ancestral, and not 
secondarily acquired, is gaining ground,’’ and the author believes that 
the bilateral water pores may be homologous with a pair of nephridia. 
The later history of the Enteroccels is described. 
ENTOMOLOGY.! 
Entomology at Washington.—Three entomological societies 
_™met at Washington, in connection with the Association of Agricultural 
Colleges and Experiment Stations and the A. A. A. S., during the 
week of August 15th to 22d. These were the Section of Entomology 
of the Experiment Stations, the Association of Economic Entomolo- 
gists, and the Entomological Club of the A. A. A. S. Besides these 
gatherings many papers upon entomological subjects were read before 
the Society for the Promotion of Agricultural Science and Section F 
of the A. A. A. S. Many entomologists were present at these 
meetings from various states, and the entomologists of Washington 
added greatly to the interest taken in these meetin 
ECTION OF ENTOMOLOGY OF EXPERIMENT STATIONS. —The opening 
session of this section was held on Saturday afternoon, August 
15th, at the Columbian University, and consisted of a discussion of 
the proper duties of the entomologist of a station, Nearly all the 
members present held that so far as practicable but few subjects 
1 Conducted by Prof. C. M. Weed, Hanover, N, H. 



