186 DE. C. CHILTON ON THE SUBTEEEANEAN 



be almost subcbelate ; in tbe female tbe f ourtb pair is simple like tbe preceding. Tbe 

 statement tbat the first four are attached to tbe body at tbe anterior ends of tbeir seg- 

 ments and tbe last three at tbe posterior ends, although true enough of tbe typical species, 

 required some modification in the case of P. austmlis, for tbe last three pairs in this 

 species are attached to tbe centres of their segments, tbe epimera occupying almost all 

 tbe inferior margins, and this is also true in a modified degree of tbe other species. Tlie 

 point tbat I wished to bring out would be better expressed by saying tbat tbe legs are 

 divided into an anterior series of four and a posterior series of three, and this would apply 

 equally well to tbe three species. 



3. " Abdomen long " should perhaps read " pleon long " in order to be consistent with 

 the term " pleopoda " used afterwards. Tbe term " uropoda " is again a very convenient 

 one to use in place of " sixth pair of pleopoda." 



4. The peculiarities of tbe pleopoda, as shown in the descriptions given below, are, no 

 doubt, quite worthy of being mentioned among the characters of the genus, but they 

 cannot be observed without dissection, and so long as tbe genus can be sufficiently dis- 

 tino'uisbed by other points more easily observed, there is no necessity to introduce them. 

 Perhaps some of them, such as the possession of an " epipodite," will prove to be 

 characters of the family and not merely of tbe genus. 



Phreatoicus assimilis, sp. nov. (Plates XVI. & XVII.) 



Phreatoicus typicus, Chilton, New Zealand Journal of Science, ii. p. 89 (March 1884). 



Phreatoicus typicus (pars), Thomson and Chilton, Transactions New Zealand Institute, vol. xviii. 

 p. 151. 



Specific diaff-iiosis. Body somewhat stout. Pleura of the second, third, fourth, and 

 fifth segments of tbe pleon very largely developed, much deeper than tbeir respective 

 seo'ments ; the inferior margins somewhat sparsely fringed with small spinules. The 

 projection at the extremity of tbe telson not much produced, broader than long; upper 

 angle of its extremity sharp and tipped with a few setae ; lower angle rounded. LoAver 

 antenuEe about half as long as the body ; peduncle with tbe fifth joint only about half as 

 long again as tbe fourth ; flagellum much longer than the peduncle. Legs stoutish, 

 with tbe joints somewhat expanded, all tbe pairs well supplied with setae. Lower lip 

 with each half ovate, with the extremity well rounded. Inner lobe of tbe first maxilla 

 rather narrow and with only four plumose setae at its extremity. 

 Colour. Translucent. 



Lenxjth. About balf an inch (10 to 12 mm.). 

 Eahitat. Winchester, South Canterbury, in wells (D. L. Imoood). 



Detailed Description. 



Tbe following detailed description is mainly taken from a male specimen tbat was 

 dissected for the purpose. A few points regarding the surface of the body &c. have been 

 taken from a female specimen that was mounted dry on a slide. 



Body (PI. XVI. fig. 1). The female specimen has tbe body 10-5 mm. long, and the perteon 

 about I'o mm. deep. The body is of uniform breadth throughout its whole length. In 



