230 A HISTORY OF EECENT CRUSTACEA 



varieties of one great type.' In Glyphocrangon aculeatus, 

 A. Milne-Edwards, the carapace is ornamented with eight 

 carinee, but in GlypJiocrangon gramdosus, Spence Bate, 

 there are five on each side of the median line, besides a 

 small central one on the rostrum. The telson in this 

 genus is described as a long bayonet-shaped organ, which 

 the animal during life has the power of locking in a fixed 

 position, so as to render it a very powerful weapon of 

 offence, and of again unlocking at its own will. When 

 fixed for striking it is supported in position by having a 

 strong cusp or tubercle on its dorsal surface brought into 

 contact with a curved process of the preceding segment. 

 Glyphocrangon rimapes, Spence Bate, was trawled in the 

 South Atlantic from a depth of 1,715 fathoms, and it is ; 

 noted as an instructive coincidence that in Willemoesia 

 leptodactyla, obtained in the same haul, the organs of 

 vision are reduced to a rudimentary condition, while in 

 Glyphocrangon they are unusually large. 



Nikoides, Paulson, 1875, is distinguished from Nik a by 

 having an exopod on the first pair of feet, and by subdi- 

 vision_pf the fourth joint as well as of the fifth in the 

 second pair. The type Nikoides Dance is from the Red Sea. 



Family 2. Alplieidce. 



The rostrum is minute or of moderate size ; the eye- 

 stalks are short, and more or less covered by the projection 

 of the frontal margin of the carapace ; the mandibles have 

 a cutting edge distinct from the molar process, and a one- 

 or two-jointed ' palp ; ' the first pair of trunk-legs are 

 robustly chelate, sometimes unsymmetrical, the second pair 

 are long and slender, minutely chelate. 



Spence Bate makes a two-jointed mandibular ' palp ' 

 a character of the family, but in describing his own genus 

 Paralplieus, he says that it is uniarticulate, and in Alpheus, 

 Fabricius, ' three-jointed,' the latter being probably a slip 

 of the pen for two-jointed. Ten or more genera have 

 been assigned to the family, two of which occur on the 

 coasts of Great Britain. 



AlpUeus, Fabricius, 1778, has a short pointed rostrum, 



