lf<82.] CRUSTACEANS FROM MAURITIUS. 543 



chitiiious and membranaceous portions of this segment, situate one 

 in the median line and one on each lateial margin ; the lateral mar- 

 gins of the second to sixth postahdominal segments are divided into 

 several somewhat triangulate lobes or teeth. The eyes are short, 

 and in a dorsal view are completely contained within the orbits ; the 

 antennules are short, and terminate in two flagella, whereof one is 

 ■ much thicker than the other. The large leaf-like external processes 

 of the antepenultimate joints of the antennae terminate in a small 

 spine at their antero- external angles, behind which are two teeth 

 on their outer margins, and have a small tuberculiform tooth on 

 their inner margins ; the terminal antennal joints are somewhat 

 obtusely angulated at the distal extremity, and have their margins 

 minutely crenulated or serrated; the outer maxillipedes are small, 

 with the ischmin as long as the merus joints. The legs are short, 

 concealed beneath the carapace, with the margins of the joints angu- 

 lated ; the dactyli of all are strong, slightly curved and acute ; the 

 antepenultimate joints have a short spine at the distal ends of their 

 upper margins ; the coxal joints of the fifth legs bear a strong spine. 



Colour (of dried ea;Myj«) reddish-yellow, with darker reddish mark- 

 ings on the sides of the branchial regions of the carapace and of the 

 postabdomen, on the inner margins of the antepenultimate joints of the 

 antennae and of the legs. Length of the body about 1 inch 3 lines 

 (32 mm.), greatest breadth about 8^ lines (18 mm.). 



Three cast shells are in the collection. 



From the Mediterranean Pseudibaeus veranyi, Guerin\ this species 

 is distinguished by the very different tuberculation of the carapace, 

 and the emargination of its lateral margins, the closed median fissure 

 of the rostrum, &c. These characters will also suffice to distinguish 

 our species from the Californian ibrm described by Prof. S. I. 

 Smith^ as Evibacus princeps, but which I think can scarcely be gene- 

 rically distinct from Pse?«rfi6«CM5. I', pfeferih most nearly allied to 

 an Atlantic species described by Dr. G. Pfeffer in his memoir already 

 referred to^ as Pseudibaeus gerstaecleri, which, however (as it 

 would appear from the description), has the carinae of the carapace 

 differently disposed, and has no meiiian depression on the cardiac 

 region, but in place thereot a continuous median keel ; moreover no 

 mention is made of any spines at the distal ends of the antepenul- 

 timate joints of the ambulatory legs. I must therefore consider our 

 species distinct from P. gerstaeckeri ; and I have much pleasure 

 in associating with it the name of the author of that important 

 memoir, which is o( much value to the student of the classification 

 of this group. 



EXPLANATION OF PLATE XXXVI. 



Fig. ] . Palinurus lonyimanus, var. mauritianus (p. 540) male adult, nat. size- 



2. Pseudibaeus i^fefferi, p. 542, Xlg^ diam. 



3. Inferior view of the same, X 1^ diam. 



' Eev. et Mag. de Zoologie, vii. pp. 139, 140, pi. v. (1855). 



^ Amer. Joiirn. Sci. and Arts, xlii. p. 118 (1866). 



^ Verliaudl. uaturwisseusch. Yereins Hamburg-Altona, p. 51 (1881). 



