GENERA CUMA, ALAUNA, AND BODOTRIA. 823 



all the specimens which I have dissected, I have found a suture 

 running across this segment, immediately before the middle part of 

 it ; this is observed very distinctly in the Cuma trisinnosa, in the 

 Bodotria areno&a, and also in the genus Alaxmia. The first of 

 these parts I consider to be the head ; the second part as the first 

 thoracic segment. To the first we find attached the rostrum, eyes, 

 antennae, organs of the mouth, and footjaws four in number. The 

 second part bears the first pair of true ambulatory legs ; these legs 

 constituting (according to M. Edwards) the third pair of foot- 

 jaws. 



" The second thoracic segment is quite obsolete in M. Edwards's 

 species (Cuma Audouinii) ; it is but slightly observed in the G. 

 Edwardsii ; in the C. trlspinosa, however, it becomes quite ap- 

 parent, being of considerable breadth at the dorsal portion. In the 

 Alauna rostrata, also, we find this segment quite developed through- 

 out its whole extent, and the second pair of thoracic legs arising 

 from it. 



" These two thoracic segments (the first and second) bear the 

 compound legs in the genera Cuma and Bodotria, in which two 

 genera the four following segments bear the four pairs of simple 

 legs. In the genus Alauna, however, we find a different arrange- 

 ment, there being an equal number of simple and compound legs, 

 three pairs of each. 



" The eyes in this tribe of animals are exceedingly small ; they 

 are pedunculated, but sessile,* and are placed very close together ; 

 they are situated near the posterior part of the head, a short dis- 

 tance behind the rostrum, and on the mesial line. They are covered 

 by the shell, owing to which, and their proximity to one another, 

 the animal is at first sight apt to be considered as monoculous. The 

 rostrum is short and truncated in the genus Cuma ; is almost al- 

 together awanting in Bodotria, but is well developed in Alauna, 

 being of considerable length and pointed. 



" The antennae undergo considerable changes in the different 

 genera of this tribe. In Cuma we find the superior antennse con- 



* This passage appears to be inconsistent. The two great families of Mala- 

 costroca are essential!}' distinguished from each other by the eyes being relatively 

 pedunculated (PodophiJialma) or sessile {Edriophthabna). — T. B. 



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