MARINE ISOPODA OF NEW ENGLAND, ETC. 



371 



Specimens examined. 



VIII. LIMNOEIID^B. 



Body compressed ; antennulre arid antennae short, subequal ; mandi- 

 bles palpigerous, formed for gnawing; feet not prehensile, all similar, 

 with short, robust dactyli ; epimera united with the thoracic segments ; 

 pleon of six distinct segments ; pleopods similar in form throughout ; 

 uropods lateral, biramous. 



This family as constituted above contains the single genus Limnoria 

 Leach, which appears also to contain but few, or perhaps a single, species* 

 of wide distribution. This genus was placed in the tribe Asellotes 

 homopodes with the Asellidce by Edwards, without, however, having 

 examined the animals himself. He has been generally followed in this 

 arrangement by later authors. Previous authors had associated the 

 genus, as it appears to me more justly, with Splicer oma and the Gymo- 

 thoidce in the wide signification of the latter term. White, in his List 

 of British Crustacea, used the name Limnoriadce to include this genus 

 with the Asellidce. I have preferred to constitute a new family for the 

 genus, which has, however, evident relations with the Splmromidce, and 

 perhaps should yet be united with that family. 



Under the circumstances family characters can scarcely be separated 

 with certainty from those of generic or even of specific value only, but 

 for the purpose of comparison with other families certain important char- 

 acters may be here stated. The body is somewhat depressed dorsally, 

 but is also compressed at the sides, and when extended is sub vermiform. 

 It is nearly capable of being rolled into a ball, as in the genus Spliceroma. 

 The head is of moderate size and strongly rounded above, as in Splice- 

 romcij and the eyes are widely separated and on the sides of the head, a 

 condition not usual in the Asellidce. The antennulse are short and stout 

 and the basal segment is but little larger than the second ; the flagellum 



*It is perhaps hardly necessary to remark that L. xylophacja Hesse, Ann. Sci. nat., 

 tome x, p. 101, pi. ix, 1868, is not an Isopotl. According to Prof. Smith it is Chelura 

 terebrans Phillipi, a boring amphipod often found associated with Limnoria^ 

 article by that author in the Proceedings of the U. S. National Museum, 

 pp. 232-235. 



