554 r.lE.SHWATER ENTOMOSTEACA OF N.S.W. ii. COPEPODA, 



Division 1. CALANOIDA. 



Cephalotlioras broader than the abdomen, with whicli it very movably articu- 

 lates. Antennules elongated, those of the male transformed, either by a re- 

 duction in the nuniber of segments or by the one being genieulated. Antennae 

 biramous, endopodite biartieulate, exopodite multiarticulate. Five pairs of legs, 

 tlie last of which are prehensile in the male. Single ovisac, when present, at- 

 tached, ventrally tq the genital segment. A well-developed heart present. There 

 are three freshwater families, but the majority of the Calanoida are marine. 



Key to families of the Calanoida. 



A. 5th pair of legs (2) natatory Centropagidae. 



AA. 5th pair of legs (?) not natatory. 



B. Endopodites of 5th legs (S) absent Temoridae. 



BB. Endopodites of 5th legs (?) present Diaptomidae. 



Family DIAPTOMIDAE. 



Abdomen short, composed of 2 or 3 segments in the female and 5 in the 

 male; last segment of the cephalothorax with the lateral parts expanded in the 

 female; caudal rami short. Antennules composed of 25 segments, the right one 

 in the male geniculate. Antennae with the exopodite longer than the endopodite 

 and seven-segmented. First pair of legs with endopodites composed of two 

 segments, those of the next three pairs composed of three segments; fifth pair 

 in th« female with small simple endopodites and three-segmented exopodites; 

 fifth pair in the male, with the right leg larger than the left and provided with 

 a movable claw. Ovisac present in the female. Two genera are included in this 

 family, one of which is represented in Aitstralia. 



Genus D i a p t o m u s Westwood, 1836. 



Syn. — Glaucea Ivoch, Cyclopsina M.-Edw. (part). 



Lateral expansions of last segment of cephalothorax biangular, armed with 

 two small denticles. Abdomen in the female 3-seg-mented, of which the genital 

 segment is much the largest, second segment very small. First pair of legs 

 with the last joint of the exopodites armed with only one spine outside. One 

 hundred and sixty-two species of this genus have been described, nearly all of 

 which are only represented in the northern hemisphere, its place being taken in 

 the southern by Boeckella and allied genera. King mentioned four species of 

 Biaptomus in 1855 {B. pollux, B. maria, B. eookii and B. uxorius), but no 

 •description or figiires exist. It is probable that the specimens he referred to be- 

 longed to the genus Boeckella which is well represented in the vicinity of Sydney, 

 since no species of Biaptomus has as yet been found south of Casino, on the 

 north coast of N.S.W. Playfair recorded finding B. gracilioides in the Richmond 

 River, but some doubt exists as to this being a correct identifica.tion. It is there- 

 fore only certain that one species of the genus occurs in New South Wales. 



DiAPTOMUS ORiENTALis Brady. 



First described by Brady (1885), recorded from Australia by Sars (1889, 

 Plate vii.. Figs. 12-16'; Plate viii.. Figs. 1-4). 



Female. Cephalothorax strongly built, tapering anteriorly; lappets of the 

 last segment broadly expanded, their outer corners pointed and their inner 

 corners rounded. Abdomen composed of two segments, the firet of which is 



