ISOPODS OF NORTH AMERICA, 505 



are short and powerfully subchelate. The branchial appendages are 

 arborescent and pendulous; to the inner extremity of which two 

 appendages are attached, each of which inversely increases as the 

 other decreases; so that one is largest nearest the pereion of the 

 animal, while the other is longest nearest the caudal extremity. To 

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

 seventh pair of pereiopocla." SPENCE BATE." 



IONE BREVICAUDA Bonnier. 



lone brevicauda BONNIER, Trav. de la Station Zool. de Wimereux, VIII, 1900, pp. 

 248-250, pi. iv. 



Localities. California, at San Francisco, on Callianassa William 

 Stimpson; Gulf of Georgia. 



The adult female measures 6.7 mm. and differs at first sight from 

 lone thoracica and lone vicina in the compact form of the body and 

 the large dimensions of the dorsal surface, which is perfectly symmet- 

 rical; the pleural lamellae of the first thoracic segments do not present 

 the differences in dimensions of the other species of the genus; those of 

 the first 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 and 

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

 part; finally the pleural lamallae 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 first 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 maxillipeds is exceedingly re.duced and is 

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

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

 much larger and that the secondary lamellae 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 carime) of the basis are more accentuated. The 

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

 species and, as with them, are covered on their external parts with 

 simple or bifid hairs having rough extremities; the only difference 

 to be noted is that, in the first oostegite (lamella), the digitatioris of 

 the inner ridge are much smaller and more numerous and there is also 

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



Brit. Assoc. Adv. Sci., 1863, XXXII, p. 98. 



