286 ME. GEOEGE M. THOMSOIS' ON A FEESHWATEE 



species. Among these was also found a single specimen of Phreatoicus australis, Chilton, 

 previously only obtained from water springs and marshy ground on Mt. Kosciusko in 

 New South Wales at a height of 5700 feet. The type species, P. typlcus, Chilton, is 

 eyeless, and occurs in the subterranean waters of Canterbury, New Zealand. The genus 

 FJireatoicus, as Dr. Chilton has shown *, is an archaic one ; it is, indeed, a remarkably 

 generalized form of Isopod. 



I have given the new shrimp the following systematic position in the above paper, 

 the name Anaspides being suggested by the total absence of carapace. 



Tribe SCEIZOPODA. 

 Eamily ANASPID^. 



Carapace wanting ; the cephalon and all the segments of the body distinct. Maxilli- 

 peds and succeeding seven pairs of limbs uniform in general structure, adapted for 

 walking, furnished with external lamellar branchise. No egg-pouch (?). Pleopoda with 

 well-developed natatory exopodites; endopodites of first and second pleopoda specially 

 modified in the males as copulatory appendages. Uropoda normal. Auditory organ in 

 the base of first pair of antennae f. Peveloj)ment ? 



Genus Anaspides. 



Anaspis, mihi. Trans. Roy. Soc. of Tasmania for 1892, p. 51. 



Integument thin and flexible. Whole body divided into 15 distinct (subequal) segments, 

 viz. one cephalic, eight thoracic, and six, abdominal. Eyes well developed. First 

 antennpB with 3-jointed peduncle and two flagella ; second antennfe with well-developed 

 scale on the second joint. Mandibles with 3-jointed palps. First maxillae 2-branched ; 

 second pair 4-branched. Maxillipeds pediform, with two rudimentary branchiae 

 projecting externally from the coxa ; exopodite small and rudimentary. Legs generally 

 uniform in structure, 7- or 8-jointed, each furnished with a claw-like dactylos. The coxa 

 of each leg (except those of the last pair) bears two external lamellar branchiae which 

 project forward, and the basos bears a well-developed natatory exopodite. Pleopoda with 

 a rudimentary endopodite in the females and in the 3rd-5th pairs in the males. First 

 pair in the males with the endopodite developed into a lamelliform organ (penis ?) ; 

 second pair with the same organ produced into a clasping-process. Telson short, rounded. 

 Uropoda with both plates subequal ; inner wdth a slight longitudinal median ridge ; 

 outer with an imperfect transverse articulation near the middle. 



External Form. 



The most remarkable and characteristic features of the body (PI. XXIV. fig. 1) are (1) 

 its separation into 15 distinct segments without any trace of a carapace, thus recalling 



* " On a new and peculiar Preshwater Isopod from Mount Kosciusko,'' by Chas. Chilton, M.A., D.Sc. Eeeords 

 of the Australian Museum, vol. i. no. 8, p. 149, 

 t This character is not in the original diagnosis. 



