ISOPODS OF NORTH AMERICA. 



57 



Description of null c — This species is closely related to Gnathia 

 hirsuta (Sars), but ditt'ers from all other species of the genus in the 

 structure of the mandibles. 



The l)ody is very short; the thorax is a litlle narrower than h>no' in 

 the median line. The fourth free segment of th(^ thorax (fifth seg- 

 ment) is scarcely longer than the fifth segment. Th(> tifth free seg- 

 ment (sixth segment) has hirge latc^ral areas, 

 posteriorly very much elongated, with the 

 posterior angles subrotund. 



The abdomen in the specimen is ahnost 

 entirely wanting. 



The head and the first two free segments 

 of the body are very rough and ornamented 

 with acute processes and numerous tuber- 

 cles; the third free segment (fourth seg- 

 ment) is ornamented with smaller tubercles 

 at the anterior portion, but is smooth poste- 

 riorly; the fourth free segment (fifth seg- 

 ment) has hxrge swollen lateral areas, orna- 

 mented with a few^ tubercles, the median 

 part being smooth; the fifth free segment 

 (sixth segment) is smooth. The eyes are 

 rather large, manifest. The mandibles are 

 large, ornamented on the ))asal half of the superior margin with a very 

 high crest irregularly notched or dentated. The teeth of the crest 

 have the apex rounded. 



The legs are long, rather robust, furnished with many processes, for 

 the most part, large. The body and the legs are furnished with a few 

 hairs. Length of the head and thorax together 3.1 mm. 



Onl}' a single mutilated specimen." 



«The above description is adapted froui the following description of Hansen's: 

 Specimen singuluni masculinuni sat mutilatum vidi. — Anceo hirsuto G. O. Sars 

 sat afiinis, structura niandilwlarum a speciebus omnibus mihi cognitis diversns. 

 Corpus l)revius; truncus jjaulo augustior quam in linea media longior. Segmentuni 

 (juartum lil)erum trunci segmento quinto vix longius; segmentum cjuintum areis 

 lateralibus magnis, post valde elongatis, angulis posterioribus subrotundatis. (Cauda 

 in specimine fere tola deest. ) Caput et segmenta duo anteriora libera trunci scabra, 

 processulis acutis et tuberculis permultis ornata; segmentum tertium liberum ante 

 tuberculis minoribus instructum, postice glaljrum; segmentum quartum area laterali 

 magna, inflata, tuberculis nonnullis decorata, parte media glabra; segmentum quin- 

 tum glabrum. Oculi sat magni, dilutiores. Mandibuhe magn;c, parte dimidia l)asali 

 marginis su})erioris crista valde elevata et irregulariter inciso-dentata ornata; dentes 

 crista' apice rotundato. Pedes longi, sat robusti, processulis multis, ex parte magnis, 

 muniti. Corpus pedescjue setis nonnullis instructa. — Long, capitis et trunci juncti 'A, 

 1 mm. — Hansen, Vidensk. Meddel. Naturh. Foren. i Kj0bh., 1887-88, p. 182. 



Fig. 41.— Gnathia cristata 

 (After Ha.nsen). a, Right .man- 

 dible (INNER SIDE), b, Male 



(SOMEWHAT mutilated) (EN- 



lar(;ed.) 



