113 



stance on record where a crustacean of the family Fortunidoi has been 

 found living as a "free messmate" in another animal. Others possess- 

 ing this habit have belonged, without exception, to families much lower 

 in the scale of classification. The elaborate system of coloration, and 

 the asperities on the surface of the carapace of this crab, would incline 

 us to believe that this is not its permanent place of residence. The 

 Pinnotheridce are devoid of color-markings, and their shell is more or less 

 rounded, the irregularities of the surface being removed by the con- 

 stant pressure to which it is subjected by the living walls of their dark 

 abode. 



Belonging to this new genus, and closely allied to the above, is 

 Mssocarcinus orhicularis, Dana. The arrangement of the colors on the 

 legs is almost identical in the two species; the general shape of the 

 front is similar, and there is the same smooth and shining surface. The 

 holothuricola, however, is readily distinguished by its being less orbicular, 

 and more produced transversely, and by the prominent posterior tooth of 

 the antero-lateral border. The third joint of the outer maxillipeds is 

 straight, and almost quadrangular; in orhiculare its shape is more irreg- 

 ular. In the latter the antero-lateral margin is a " little reflexed," while 

 in the former it is everted. The shape of the claws and ambulatory feet 

 is the same in both species. 



PODOPHTHALMUS VIGIL, {Fahr.) Leach. 



Podophthalmus vigil, Leach, Zool.Miscell., ii, pi. cxviii. — Guerin, Icon, do E^gne Anim. 



Crust., pi. i, f. 3.— M. Edwards, Hist. Nat. des Crust., 1, 467 ; E^gne Anim. de 



Cuvier, Crust., Atlas, pi. is, f. 1. — De Haax, Faun. Japon., Crust., 44. — Axph 



M. Edwards, Arch, du Mus. d'Hist. Nat. de Paris, 1860, x, 420. 

 Podophthalmus spinosus, Lamarck, Syst. des Anim. sans verteb., 152; Hist, des Anim. 



sans vert., v, 157. — Latreille, Gen. Crust, et Insect., i, pi. i et ii, f. 1; Hist. 



Nat. des Crust, et des Insect., vi, 54, pi. xlvi ; Efegne Anim. de Cuvier, iv, 33 ; 



Encyclop. Meth., x, 166. — Desmarest, Considerat. sur les Crust., 100, pi. vi, f. 



1. 

 Fortunus vigil, Fabricius, Suppl. Entom. Syst., 368, no. 1. 



Locality : Fanning Group of Islands, North Pacific. • 



MACEOPHTHALMIDiE. 

 OCYPODINJE. 



GELASIMUS GIBBOSUS, Smith. 



Gdasimus gibiosua, Smith, Trans. Connecticut Acad., vol. ii, 140, pi. ii, f. 1, et pi. iv, f. 8 ; 

 Eepprt of the Peabody Academy of Sciences, 1869, 91. 



Locality : La Paz, Lower California. 

 Bull. N. M. 1^0. 7—8 



