NO. 1222. ISOPODS OF THE ATLANTIC COAST— RICHARDSON. 561 



b. Buccal mass not very prominent below. First maxillte have two plumose setse 

 on the inner plate. Mandibles with molar expansion obsolete, without any 

 trituratini; surface, it ])eing replaced by brushlike recurved seta\ 



c. External antennte generally long, close together, with antennal openings large. 

 Body as a rule scarcely able to be contracted into a ball. Head less mani- 

 festly immersed in iirst thoracic segment. Lateral parts of the head sep- 

 arated by a vertical marginal and inframarginal line. Clypeus arched. 

 Legs generally long. Uropoda produced, reaching beyond the terminal 

 segment of the abdomen and the preceding segment. Terminal segment 

 narrower than preceding ones and usually conically produced at end. 



Family "XIX. Oniscid.e (p. 561). 



f^. External antennae generally short, with antennal openings small. Body 

 able to be contracted into a ball. Head immersed in first thoracic segment. 

 Lateral jiarts of the head undifferentiated. Clypeus perpendicular. Legs 

 generally short. Uropoda short, not reaching beyond the terminal segment 

 of the abdomen or the preceding segment. Terminal segment short and 



broad Family XX. Akm.\dillidid.e (p. 569). 



y. Buccal mass prominent. First maxillae have three plumose setae on the inner 

 plate. Mandibles with molar expansion large and broad, exhibiting a finely 

 fluted triturating surface. 



c. Head without any lateral lobes, frontal part rounded. Eyes well developed 

 or wanting. Inner antenn;e with last joint verj- small and withoutdistinctly 

 developed sensory filaments. Posterior maxilhe with two thic^i hairy bris- 

 tles. Maxillipeds with terminal part distinctly five-articulate, masticatory 

 lobe truncate at tip, epignath short. External sexual appendages in male 

 double. Inner branches of first pair of pleopoda of a similar structure in 

 both sexes, that of second pair in male terminating in long stylet. Both 

 l)ranches of uropoda styliform Family XXI. Ligiid.e (p. 574). 



c'. Head with distinct, though not very large, lateral lobes, front more or less 

 produced. Eyes small or wanting. Inner antennae with last joint well 

 developed and tipped with a number of delicate sensory filaments. Posterior 

 maxillaj without any bristles. Maxillipeds with terminal part generally 

 imjDerfectly articulated, masticatory lobe terminating in a thin lash, epignath 

 narrow, linguiform. Sexual appendage of male simple; inner liranch of 

 both first and second pairs of pleopoda transformed for copulativi* purposes. 

 Uropoda with branches conically tapered. 



Family XXII. Trichoxiscik.e (p. 575). 



Family XVIII. TYLIDES. 



59. TYLOS Latreille. 

 138. TYLOS NIVEUS Budde-Lund. 

 Ti/los niri'us BrDDE-Lu.\D, Crust. Isop. Terrestria, 1885, \)\). 278, 279. 

 Hahltat. — Ke}- West, Florida. 



Family XIX. ONISCID.E. 



.\NALYTRAL KEY TO THE GENERA OF ONISCID.E. 



. External opercular ramus of the abdominal appendages containing no sjiecial 

 respiratory organ. Flagellum of external antennae triarticulate. 

 1). Epimera of thoracic segments large, with all tlie posterior angles acute. Abdo- 

 men not abruptly narrower than thorax. First two abdominal segments 

 very short, three following ones large, with large acute epimera. 

 Proc. N. M. vol. xxiii 36 



