500 CRUSTACEA MALACOSTRACA. 



abdomen well developed, usually with seven segments, and with 

 the three anterior feet differing in shape from the three posterior. 

 Branchiae lamellar. 



Division 1. GAMMARINA 



Head and eyes small ; antennae alike or nearly so in the two sexes ; 

 maxillipeds with multiarticulate pediform palps. The two anterior 

 pairs of legs (belonging to the 2nd and 3rd thoracic segments) frequently 

 end in prehensile claws, and iri many cases the proximal segment in the 

 four anterior, the two proximal segments in the three posterior pairs are 

 widened to lamellae. 



Tribe 1. COROPHIINA. 



Body not compressed, half cylindrical ; mandibular palp present, the 

 basal joints of the thoracic legs short, antennae strongly developed. 



Fam. 1. Cheluridae. Anterior antennae with an accessory flagellum, 

 posterior with a setose lancet-shaped plate in place of a flagellum. The 

 seven posterior thoracic segments all free, and approximately equal. The 

 4th-6th abdominal segments fused. The 3 last abdominal feet large and of 

 peculiar shape. Chelura Phil. Bores in submerged timber, destroying dock- 

 works. Europe and America. 



Fam. 2. Dulichidae. Both antennae with strong, elongated shafts and 

 short flagella. The seventh and eighth thoracic segments fused, and the 

 6th-8th thoracic legs very long, the two anterior pairs with a prehensile 

 blade ; 4th and 5th abdominal segments fused, and one of the terminal 

 pairs of abdominal legs absent. Dulichia Kroyer ; Laetmatophilus 

 Bruz. ; Xenodoce Boeck. all N. Sea ; Cyrtophium Dana, Atlantic, etc. 



Fam. 3. Corophiidae. Both antennae with elongated setose shafts. 

 The segments of the thorax and abdomen all distinct. 4th and 5th 

 thoracic legs with unicellular glands. The 3 terminal abdominal legs 

 and sometimes the terminal body segment furnished with spines or hooks, 

 by which the animals maintain their position in the tubular cases or 

 passages which they construct. Corophium Latr. 2nd antennae very 

 long ; Siphonoecetes Kroy. ; Cerapus Say ; Dercothoe Dana ; Unciola 

 Say ; Hela Boeck ; Podocerus Leach ; Gammaropsis Lilljeb. ; Aora 

 Kroy. ; Xenocheira Hasw. ; Stimpsonia Sp. Bate ; Dryope, Sp. Bate ; 

 Cratippus Sp. Bate ; Podoceropsis Boeck ; Amphithoe Leach ; Synam- 

 phithoe White ; Protomedeia Kroy. ; Microprotopus Norm. ; Gossea 

 Sp. Bate ; Goesia Boeck ; Xenoclea Boeck ; Haplocheira Hasw. ; Amphi- 

 thoides Kossm. 



Fam. 4. Icilidae. Body broad and depressed. Head broad in front, 

 with projecting eyes. Icilius Dana ; Icridium Grube ; Phlias Guer. 



Tribe 2. GAMMARINA GENUINA. 



Body much arched, laterally compressed, though with rounded thoracic 

 terga. Basal joints of the second to the fifth thoracic legs generally 

 large, sometimes very large. Antennae small. 



Fam. 6- Gammaridae. With the characters of the Tribe. (The 

 branchiae are not spirally twisted in Subfamilies 1-5). 



Sub-fam. 1. Lysianassina. Head small, depressed, truncated in 

 front, or indented by the base of the anterior antenna. The shaft 

 of this appendage is thickened and its two terminal segments very 



