116 



THE VOYAGE OF H.M.S. CHALLENGER. 



directed forwards. External maxillipedes subpediform, with the ischium and merus 

 narrow and frequently spinose internally. Eyes placed in very incomplete orbits. 



The representatives of this section occur in all seas, but only the two genera Galathea 

 and Munida are found in shallow water. So slight and at the same time so numerous 

 are the modifications met with in those parts of the body from which the generic 

 characters are derived, that it is questionable whether many of the deep-water (so-called) 

 genera should not be united ; the examination of a number of species shows at least that 

 in otherwise closely allied forms there is considerable variation in the form and armature 

 of the rostrum, carapace, chelipedes, and external maxillipedes. The number of gills in 

 most if not all the genera' agrees with that of the Porcellanodea, viz., fourteen on each 

 side, arranged as follows : — 



The genera as at present constituted may be arranged in two divisions, forming a 

 single family: — 



I. Abdomen simply bent. 



a. Eyes normal. Many of the species inhabiting shallow water. 

 Galathea, Fabricius. 1 ? Gnmothea, Leach. 



Munida, Leach. 



h. Eyes non-pigTnented. Species confined to deep water. 



Munidopsis, Whiteaves. 

 Elasmonotus, A. Milne-Edwards. 



? Anoplonotus, S. L Smith. 

 Galacantha, A. Milne-Edwards. 



II. Abdomen folded on itself Species confined to deep water. 



Eumunida, S. I. Smith. | Ptychogaster, A. Milne-Edwards. 



Uroptychus, Henderson. 



Family Galatheid/E. 

 Galatheidx, Dana, U.S. Explor. Exped., vol. xiv., Crast., part ii. p. 1431, 1852. 



' I have examined the branchiae in various species of Galathea, Mumda, Munidopsis, Elasmonotus, Galacantha, and 

 Uroptychus. 



