STALK-EYED CRUSTACEA 237 



c^. The third and fourth joints of the 

 external maxilh'pedes close completely the OifC 



buccal cavity, and have no rhomboidal space \\ /^<^ 

 between their internal edsjes. — (Uca.) rr 



I. Geocarcinus. 



Geocarcinus .... Leach, H. Milne Edwards, 



Miers. 



Carapace with the mesogastric and cervical sutures 

 strongly defined. The antero-lateral margins not dis- 

 tinctly dentated. The front is narrow, anteriorly truncated, 

 nearly reaches the anterior margin of the buccal cavity, 

 and almost completely covers the internal antennae. 

 Orbits with the superior margin subentire, no distinct 

 tooth at the exterior angle, and with a well-marked 

 hiatus in the inferior margin, near the interior subocular 

 lobe, which is in contact with the front, and excludes 

 the short antennae from the orbit. The eyes are set on 

 rather short, thick pedicles. 



The antennae are very short, and occupy the angle 

 formed by the contact of the inner subocular lobe of the 

 orbit with the front ; their basal joint is slightly dilated 

 and does not reach the frontal margin. No distinct 

 ridges are developed upon the endostome or palate. 

 The external maxillipedes bulge out externally, and 

 inclose a lozenge-shaped interspace; third and fourth 

 joint are broad ; the third joint is not produced at the 

 antero-internal angle ; the fourth is distally rounded and 

 conceals the next joints, it has sometimes a fissure in the 

 antero-lateral margin ; the fifth joint is articulated to it 

 on its inner surface. The first pair of legs of the adult 

 male is considerably developed, and usually unequal ; 

 fourth joint trigonous and somewhat elongated ; fifth 



