THE MOTHEE LOBSTEE 193 



Savigny's fine folio plate its characteristics are beautifully 

 delineated. The enormously broad ultimate and antepen- 

 ultimate joints of the second antennas will astonish and 

 perplex any one who for the first time becomes acquainted 

 with a crustacean of this family. In the present species 

 the quadrangular rostrum, the little eyes very wide apart, 

 and implanted at a little distance from the sharp anterior 

 angles of the great oblong tuberculate carapace, the com- 

 parative smallness of the legs entirely unch elate, and the 

 breadth of the tail-fan, are characters which will attract 

 and deserve attention. 



Themis t Leach, 1819, has still only the type species, 

 Thenus orientalis (Fabricius), in which the carapace is 

 broader than long, with a bilobed rostrum, and the eyes 

 placed on visible stalks at its anterior angles. There are 

 twenty-one pairs of branchiae. 



Ibdnus, Leach, 1815, has the carapace much broader 

 than long, deeply incised on the sides, with a bilobed 

 rostrum, and the small eyes planted far from the front 

 angles; the broad second antennas not very remote on 

 their inner margins, the pairs of branchias twenty-one or 

 twenty-two. Species of this remarkable genus are dis- 

 tributed all over the Eastern seas, but Ibacus verdi, from 

 St. Vincent, Cape Verde Islands, and also from Sambo- 

 angan in the Philippines, is said to afford the only speci- 

 mens of the genus taken elsewhere than along the Pacific 

 coasts of Asia and the Australasian Islands. ' Hence,' 

 Spence Bate who instituted the species observes, 'the 

 similarity that it bears to Ibaccus indsus (Peron) is the 

 more remarkable, and, judging by the several figures 

 and descriptions published, the differences are slight, 

 except in the character and number of the dentations that 

 arm the margins of the carapace and antennae.' He also 

 calls attention to the thinning out of the sharp lateral 

 margins to an extent equalling that of some of the 

 Brachyura. Moreover, while the cervical groove, often so 

 conspicuous in the Macrura, is here wanting, the lateral 

 notches are greatly deepened, and widely separate the 

 suborbital and hepatic regions from the branchial. As in 



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