ISOPODA. 489 



less completely into a ball. A posterior backward pointing dorsal spine- 

 is frequently present. Limnoria Leach, L. lignorum White, known at 

 Plymouth as " the Gribble," gnaws out burrows in submerged wood- 

 work ; Sphaeroma Latr. ; Cymodoce Leach ; Cerceis M. Edw. ; Amphoroi- 

 dea M. Edw. ; Cassidina M. Edw. ; Naesa Leach ; Campecopea Leach ; 

 Ancinus M. Edw. 



Fam. 3. Serolidae. Very broad and depressed Isopods, with the 

 head sunk in the thorax. The second (and in the male the third) thoracic 

 leg ends in a clasping foot, succeeding legs long and slender. The three- 

 posterior abdominal segments fused, three anterior abdominal appendages 

 are setose swimming feet, the 4th and 5th respiratory, and the 6th narrow. 

 Serolis Leach. 



Fam. 4. Aegidae. Body oval or elongated, not rolling into a ball ; eyes- 

 usually large, first antennae usually conspicuously shorter than the 2nd. 

 Both- arise from the front margin of the head. The 2nd-4th thoracic legs 

 short and directed forwards, the three posterior pairs do not end in hooks. 

 Abdominal segments distinct. The 6th abdominal legs forming a fan- 

 shaped swimming tail with the shield-shaped terminal segment of the body, 

 Sub-fam. 1. Cirolanina. With biting mouth parts. Conilera, 

 Eurydice and Cirolana Leach ; Tachaea Schiodte ; Corallana Dana ; 

 Barybrotes Schiodte. Intermediate genus Bathynomus A. M. Edw. 

 B. giganteus A. M. Edw. 9 in. long, at 955 fthms. between Cuba 

 and Florida, also in Indian Ocean. Respiration carried on by means 

 of branching processes of the endopodites of the abdominal appendages. 

 Eyes very large, directed ventrally. 



Sub-fam. 2. Aegina. With sucking mouth parts. Aega Leach. 

 A. spongiophila Semper, inhabits the siliceous sponge Euplectella, in 

 company with a species of Palaemon ; Rocinela Leach ; Alitropus 

 M. Edw. 



Sub-fam. 3. Cymothoina. Shape of body as in other sub-families 

 but antennae approximately equal, arising beneath front margin of 

 head ; mouth parts adapted for sucking ; thoracic legs short and 

 bear hooked claws ; 5 anterior abdominal segments closely com- 

 pressed and may be fused, 6th is large, shield-like, with broad 

 swimming appendages. Parasitic on bodies of fish. Aegathoa Dana ; 

 Olencira Leach ; Ichthyoxenus Herk ; Ourozeuktes M. Edw. ; 

 Harponyx Sars ; Lobothorax Bleeker ; Glossobius Sch. and M. 

 G. linearis Dana, infects the mouths of Flying Fish. Livoneca Leach ; 

 Renocila Miers ; Ceratothoa Dana ; Nerocila Leach ; Anilocra Leach, 

 A. gigantea attains 3| in. length ; Cymothoa Fab. (Fig. 298). Last 

 three genera hermaphrodite, protandrous. 



Tribe 6. EPICARIDEA. 



Parasitic on other Crustacea. Females (or hermaphrodite individuals 

 in the female phase, see below) degraded in structure and often unsym- 

 metrical, males small and symmetrical. Abdominal limbs, if present, 

 branchial and not covered by an operculum. Uropods terminal. 



Fam. 1. Microniseidae. On Copepods. Microniscus Fr. Mull, on 

 Calanus finmarchicus, etc. 



Fam. 2. Cyproniscidae. On Ostracods. Cyproniscus Kossm. C. cypri- 

 dinae (Sars) lives between the valves of the shell of Cypridina. Female 

 reduced at last to a sack of eggs. Male, attached to female, also 

 without appendages in adult state. 



