NO. 1175. ISOFODS OF THE PA CI FIG CO A S T—BICHABDSON. 861 



articulate; epignath large, flauking the basal part. Sexual appendage of 

 male simple, and generally connected with inner rami of first pair of pleopoda. 

 Uropoda, "with inner branch smaller than outer, and attached far in front of it. 



6. External antennje generally long, close together, with antennal openings large. 

 Body scarcely able to be contracted into a ball. Head less manifestly im- 

 mersed in first thoracic segment. Lateral parts of the head separated by a 

 vertical marginal and inframargiutil line. CTj'peus arched. Legs generally 

 long. Uropoda produced, reaching bej'ond the terminal segment of the abdo- 

 men and the post-terminal segment. Terminal segment narrower than preced- 

 ing ones and conically produced at end Family XIII. Oxiscid/E (p. 861). 



h'. External antennae generally short, with antennal openings small. Body able 

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

 parts of the head undifferentiated. Clypens perpendicular. Legs generally 

 short. Uropoda short, not reaching beyond the epimera of the terminal seg- 

 ment of the abdomen or the post-terminal segment. Terminal segment short 



and broad Family XIV. Ahmadillidid^e (p. 86.5). 



a'. Flagellum of outer antenn;e multiarticulate. Buccal mass prominent. First 

 maxilhe have three plumose set® on the inner plate. Mandibles with molar 

 expansion large and broad, exhibitiug a finely fluted triturating surface. 

 Maxillipeds with terminal part distinctly five-articulate; epignath short. 

 External sexual appendages in male double. Inner ramus of first pair of pleo- 

 poda of a similar structure in both sexes. Uropoda with both branches 

 styliform Family XV. Ligiid^e (p. 865). 



Family XIII. ONISCID^. 



ANALYTICAL KEY TO THE GENERA OF OXISCID^. 



a. Flagellum of external antenuai hiarticulate. External opercular ramus of the 

 first, second, and rarely of the third or all the pairs of the abdominal append- 

 ages furnished with trachea. 



h. Lateral lobes of the head large; frontal lobe more or less projecting. Eyes 

 subdorsal. First two abdominal segments generally very short; three fol- 

 lowing ones large, with large epimera. Terminal segment not reaching beyond 

 the epimera of preceding segment. Uropoda somewhat even; longer in male 

 than in female 29. rorcelUo. 



h'. Lateral lobes of head small, hardly projecting; frontal lobe obsolete. Eyes 

 lateral. First two abdominal segments scarcely shorter than those following. 

 Epimera of all the segments small. Terminal segment extending beyond the 

 epimera of preceding segment. Uropoda subequal in both sexes. 



30. Metoponorthus. 

 a'. Flagellum of external antennaj triarticulate. External opercular ramus of 

 abdominal appendages containing no special respiratory organ. 



h. Front of head produced at the middle aud at the sides in tubercles ; lateral 

 tubercles hornlike. Epimera of abdominal segments moderate or small. 



31. AlloniscHs. 



V. Front of head not produced ; with lateral lobes. Epimera of abdominal seg- 

 ments large 32. Lyprohim. 



29. PORCELLIO Latreille. 



ANALYTICAL KEY TO THE SPECIES OF PORCELLIO. 



a. Surface of body smooth. 



l. Frontal median lobe of head rounded, a little produced. Articles of the flagel- 

 lum of external antennie equal in length. Last segment of the abdomen witli 

 its extremity widely rounded 72. Porcdlio formoaua Stuxb^rg. 



