IROPODS OF NORTH AMERICA. 505 



are .short and powort'ull}' subchelate. The branchial appendai^es are 



arl)ore.s('ent and pendulous; to the inner extremity of which two 



appendages are attached, each of which inversel}^ increases jis the 



other decreases; so that one is laro-est nearest the pereion of the 



annnal, while the other is iong-est nearest the caudal extremity. To 

 the posterior of these the male animal attaches itself by means of the 

 seventh pair of pereiopoda." Spence Bate.** 



lONE BREVICAUDA Bonnier. 



lone hrevioiuula Bonmkij, Trav. <lo hi Statimi Znol. de Wiinert'ux, VIIT, 1900, pp. 

 248-2r)0, pi. IV. 



Locdlitlc.^. — C^aliFornia. at San Fi-ancisco. on (^ilUatiassn William 

 Stimpson; (hilf of (T(M)i'uia. 



The adult female measures 6.7 nun. and dift'ers at tirst sight from 

 lout' ihoi'iic'icd and lone v!cln<( in the compact form of the body and 

 the larg-e dimensions of the dorsal surface, which is perfectly symmet- 

 rical; the pleural lamella' of the first thoracic segments do not present 

 the diti'erences in dimensions of the other species of the genus; those of 

 the lirst two segments are, on the right as on the left, almost equal and 

 do not extend backward beyond the following segment; those of the 

 two following segments are smaller, and are inserted in a small antl 

 narrow portion of the pleural margin of the segment, on the anterior 

 part; tinally the pleural lumalhe of the last three segments, and 

 especially those of the sixth and seventh, are not longer than the pro- 

 longations of the entire lateral margin, the width of which they have, 

 with, moreover, some small sinuses in their inferior margin. 



The lirst four thoracic segments, moreover, have each a pair of 

 pleural bosses, regularly rounded and very distinct. The appendages 

 of the head do not present anything of importance; one can only point 

 out that the palp of the maxillipiKls is exceedingly reduced and is 

 merely a small lamella inserted in a notch and terminating in three 

 little hairs, and also that the infeiior lamella of the head is relatively 

 much lai'ger and that the secondarv lamelUe are more developed; the 

 third, the inner lamella, exists also in this American species. The 

 legs are identical with those of /. thoracica^ except perhaps the irreg- 

 ular elevations (or carin;e) of the basis are more accentuated. The 

 oostegites (or incubatory lamella^) are identical with those of the other 

 species and, as with them, ai'e covered on their external parts with 

 simple or bitid hairs having rough extremities; the only ditierence 

 to he noted is that, in the tirst oostegite (lamella), the digitations of 

 the inner ridge are nmch smallei- and more numerous and there is also 

 a ditierence in the arrangement of the hairs on the inferior margin. 



«Brit. Assoc. Adv. Sci., 1863, XXXII, \^. 98. 



