PRKFAOE, IX 



where such an acfouiit can ))o found. In another place-' a l)riet' 

 review of the l.«opod structure has already been given. 



It has not ))een considered worth while to encumber the legends with 

 detailed ex[)lanation of many of the tigures that have been taken from 

 other authorities; students, however, who desire to learn the signifi- 

 cance of the lettering not given in the illustrations, are referred to the 

 original papers. 



As a final suggestion I would like to sa}' that m}^ object in under- 

 taking this work has been to assist the student in the determination of 

 the forms by giving figures and descriptions of all the species. It is 

 to be hoped, in case of omissions or errors, that leniency will be 

 observed, for the task has not always been easy. 



Harriet Richardson, 



Washington City, Novemhcv i, 190f). 



POSTSCRIPT. 



Since this monograph has been printed, and within the last few 

 days. Dr. H. J. Hansen's paper on the Propagation, Structure, and 

 Classification of the Spha^romiche has been received.'' With a large 

 amount of material, a comparison of types from various museums all 

 over the world, and a thorough examination of specimens, Doctor Han- 

 sen has arrived at an excellent classification of this group, which has 

 heretofore been in an extreme state of confusion and so recognized by 

 all who have attempted to determine species or to refer them to their 

 proper genera. In Doctor Hansen's paper new genera have been estab- 

 lished and some old ones canceled. The changes which particulai-ly 

 affect the present paper and which I have not been able to make use 

 of in the text, inasmuch as Doctor Hansen's paper w'as received too 

 late, are as follows: The gemis Cmsidisca., new genus, must be can- 

 celed as being a synon3"ni of Hansen's new genus Cassidinldea ; Cil'i- 

 civa caudata, C. glUlann^ C. sculj/ta, and C. cordata must be referred to 

 Hansen's new genus Paracerceis. The following list shows these rela- 

 tions more exactly: Cassldisca cnmlis— Cassidmidea ovalis; Ca.s'&idisca 

 Ik II //yvy;«.s- = Cassidlnidea lunifrons,' CUlcsea caudata = Paracerceis cau- 

 data; C'dicsea gill iaru( — Paracerceis gilliana; Oilicaia cordata = Para- 

 cerceis cordata; Cllicxa scxdpta^^ Paracerceis sculpta. 



While in New Haven last summer 1 examined the second plcopods 

 of a number of cotypes of Dynainene jjerforata and found that the 

 males and females of this species were similar, with the exception that 



"Contributions to the Natural History of the Isopods, by Harriet Richardson, 

 Proc. U. S. Nat. Mus. XXVII, 1904, i)p. 4-17. 



'' Quarterly Journal of Microscopical Science, XLIX, Pt. 1. 1905, now sen, pp. 

 69-135. (Octol)cr numbor received iiere November 11.) 



