1869.] RITCHIE — ON PIERIS RAPiG. 293 



destruction of a portion of the vault. The true natural orifices 

 of this part are those that I have discovered in P. conoideus as 

 above mentioned. They are the homologues of the ovarian pores 

 at the bases of the arms of Caryocrlnus and in part, as I shall 

 show in another part of these notes, of the ambulacral orifices of 

 the true crinoids. 



With regard to the structure of the calyx of Pentremites, it is 

 generally supposed that there are only three series of plates — the 

 basal, radial and interradial. Mr. Lyon has advanced the opin- 

 ion that there are three small plates below those now called the 

 basals (Geol. Ky., vol. iii., p. 468, pi. ii, fig. Ic). I have ex- 

 amined a number of specimens with reference to this point, and I 

 think he is right. There are three small pentagonal basals, the 

 two upper sides of each are excavated to receive the sub-radials, 

 i.e., those at present designated " the basals." They are, in 

 general, anchylosed to the subradials, but in one of Mr. Lyon's 

 specimens that I have seen, they are distinctly separate. * 



(To be continued.) 



NOTES ON THE 

 SMALL CABBAGE BUTTERFLY, PIERIS RAP^. 



By A. S. KiTCHiE. 



The efi'ects produced by insects, either beneficial or injurious 

 to man, have not been studied by the people as the subject 

 deserves. Their benefits are taken as a matter of course, 

 whether in their capacity as scavengers, fertilizers of plants, or 

 as producers of silk, dyes, wax, honey, &c. ; but when injuries, 

 which affect either our persons or our property, directly or 

 indirectly, are caused by the presence of insects, the " hue and 

 cry" begins. 



More natural history ought to be taught in schools, so that 

 the habits of the many creatures composing this world of ours 

 might be better known and understood by the youth of the 

 country. 



This article, with the author's permission, is reprinted from the 

 American Journal of Science and Arts, for July, 1869. 



