328 AMniii'onA nokhalia. 



The description that Risso has f.Mvon is not so complete as to en- 

 able me to do more than ass\ime this to he the species, with which 

 his figure corresponds in general aspect. 



2. Thyropus ferns. (Plate LII. fig. 8.) 



Typhis ferus, Ediccirih, Ann. des Sc. Nat. xx. p. 395, pi. 11. f. 8 ; Hist. 

 des Crufit. iii. p. SO. 



Giien'n, Iconoyr. Crust, pi. 27. f. 8. 

 Thyropus diaphanus, Dana, tl. S. Explor. Exited, p. 1013. pi. 1(39. f. 4. 



** Superior antennae very short ; fir.st joint small, and forming nearly 

 u right angle with the second, -nhich is large, compressed, of an 

 oval form, and furnished upon the external border with long hairs ; 

 the other joints slender, cylindrical, and constituting a small ter- 

 minal flagellum, inserted at the extremity upon a kind of disk. 

 First joint of the inferior antenniB not so long as, but stouter 

 than, the two following, which ai'o nearly e(|ual, and longer than 

 the fourth and fifth together. ^Mandibles large, ha\dng an ap- 

 pendage with three joints, of which the last two arc almost of the 

 same length and are nearly as stout as the first. Pirst pair of 

 gnathopoda larger and shorter than, but of the same form as, the 

 second, having the carpus inferiorly produced neaiiy to the ex- 

 tremity of the propodos. Fourth pair of poreiopoda yearly twice 

 as large as the preceding ; three posterior pairs of pereiopoda not 

 having the same form, and scarcely passing beyond the extremity 

 of the triangular telson; antepenultimate pair having the peduncle 

 long, cylindrical, and terminating in two ovate pointed lamella? ; 

 penultimate paii' having a small peduncle and two largo ovate 

 lamellic ; ultimate pair ha%'ing the peduncle short and the lamelli- 

 form rami lanceolate." — Edwards. 



Length about 6 lines (Edtvards) : when extended, ^ of an inch ; 

 when folded, i of an inch (Dana). 



Hah. In the latitude of the Canary Islands (Edwards). Atlantic, 

 in lat. 4° 25' S., long. 21° 30' W., Nov. 7, 1838 (Dana). St. Helena 

 (MS. label, Mitseum of Jardin des Plantes). 



The only character in Dana's description which differs from that of 

 M. -Edwards, is that the last joint of the base of the superior an- 

 tennse is stated bj Dana to be multiarticulate, Avhich I am inchned 

 to believe is a misconception on the part of that generally accm-ate 

 observer. 



According to M. -Edwards's description and figiu-e, this species 

 differs from T. ovoides chiefly in the respective lengths of the joints 

 of the inferior antennse, and in having the gnathopoda furnished 

 with fine hairs instead of having the carpus and propodos serrated, 

 as in the specimen I have adopted as being that of T. ovoides, llieso. 



