CETTSTACEA. 521 



4. MensBtliius monoceros {Latr.). 



A series of specimens of both sexes and various ages are in the 

 collection from the Seychelles, 4-12 fms. (No. 194) ; also a small 

 female obtained on the beach at Mozambique (No. 224), -which has 

 the prominences or lobes of the antero-lateral margins spiniform 

 and acute. 



I have already referred to this widely distributed and variable 

 species pn p. 190. 



A small female specimen, which has unfortunately, lost all the 

 legs, obtained at African or Eagle Islands, 10 fms. (No. 184), has 

 the rostrum remarkably abbreviated, not equalling in length the 

 interocular width of the frontal region of the carapace, the greatest 

 width at the branchial regions little exceeding the width at thp 

 frontal region, and the basal antennal joint more dilated than in the 

 typical M. monoceros. It appears to merit distinction at least as a 

 variety, since I have seen no specimen in the extensive Museum 

 series which closely resembles it, but I refrain for the present from 

 designating it as such. 



5. Stilbognathus martensii. (Piaie XLVI. fig. B.) 



I propose thus to designate two males obtained at Marie-Louise 

 Island, 17 fms. (No. 186), and a male from Providence Island, 19 

 fms. (No. 217), which, although having the ischium-joint of the 

 outer maxillipedes longitudinally sulcated (and" hence certainly 

 belonging to Stilbognathus), differ from Stilboffnathus erythrceus, Von 

 Martens*, from the Eed Sea, in the form of the merus-joint, which 

 has its extero-distal angle produced and acute as in Stenocionops 

 eervicornis, and which further differs from the known species both 

 of Stenocionops and Stilbognathus in having the notch on the inner 

 margin (where the fourth joint articulates with it) provided with a 

 tooth or lobe (see fig. J). 



The carapace is constricted behind the orbits (as in S. eervicornis) ; 

 the gastric, cardiac, and front of the branchial regions are rather 

 convex and more or lees distinctly covered with small tubercles or 

 granules ; the posterior margin of the carapace is cristate and pro- 

 longed in the median line into a tooth or lobe. The spines of the 

 rostrum are slender and curved at first outwards and then inwards 

 so as to meet at the apices, which are vertically reflexed as in Ste- 

 nooionops cwwrostns, A, M.-Edwards. There is a rounded prominence 

 upon each pterygostomian region. The supraocular spines of the 

 carapace are very long and straight ; the eye-peduncles even longer ; 

 the basal antennal joint is considerably dilated, and has a small 

 spine on its outer side near the base and another at its distal ex- 

 tremity. The longitudinal pit on the outer surface of the isohium- 

 joint of the outer maxiOipedes is longer than in Stilbognathus ery- 



* Verhandl. zool.-bot. Geaellsoh. Wion, xvi. p. 379, fig. (1866). 



