475 



7. Dexamine spinosa, (Mont.). 



(PI. 166, fig. 2, PL 167). 



Cancer gammarus spinosus, Montagu, Transact. Linn. Soc. XI, p. 3, PI. 2, fig. 1. 



Syn. : Amphithoe marionis, M-Edw. 

 > Amphithoe tenuicornie, Rathke. 

 Amphithonotus marionis, Costa. 



Body rather robust, with the anterior part of the back broadly 

 vaulted. Metasome powerfully developed, especially in the male, and having 

 each of the segments produced to a strong, acute, posteriorly-pointing projection. 

 Urosome with a similar dorsal projection at the end of the 1st segment, and 

 having besides, immediately above the insertion of the telson, another much 

 smaller pointed process Cephalon about the length of the first 2 segments of 

 mesosome combined, rostral projection rather short and blunt at the tip, 

 lateral corners exserted to an acute triangular lappet. First pair of coxal 

 plates somewhat irregular in form, having the anterior edge slightly concaved 

 and forming with the strongly arcuate distal edge a conspicuous angle ; 2nd 

 pair oblong quadrangular in form; 3rd pair somewhat obliquely truncated at 

 the tip, and having the infero-posteal corner acutely produced; 4th pair fully 

 as deep as the corresponding segment, and produced posteriorly, below the 

 emargination, to a narrowly rounded lobe; 5th pair transversely oval in form, 

 with the anterior lobe terminating in a short obtuse point curved downwards. 

 Last pair of epimeral plates of metasome produced at the lateral corners to 

 a very strong acuminate projection. Eyes narrow oblong in form, and con- 

 siderably larger in male than in female, pigment dark brown, with a whitish 

 coating. Superior antennse considerably exceeding half the length of the 

 body, 1st joint of the peduncle produced at the end posteriorly to an obtuse 

 dentiform projection, 2nd joint nearly twice as long as the 1st and much narrower, 

 last joint very small, flagellum about twice the length of the peduncle, and 

 very slender, being composed of numerous (30 40) articulations, Inferior 

 antennae in female much shorter than the superior, with the last joint of 

 the peduncle longer than the penultimate one, flagellum exceeding the 

 peduncle in length, those of male much more elongated, being even longer 

 than the superior ones, and having the anterior edge of the penultimate 

 and antepenultimate joint of the peduncle densely clothed with fine sensory 

 hairs, flagellum very slender, filiform. Palps of maxillipeds without any 

 trace of a dactylus 1 ). Anterior gnathopoda short and stout, with the basal 



*) In D. Flindersi Stcbbing the dactylus is present, though not very large. 



