BY MARGUERITK HENRY. 31 



SiMOCEPHALUS AUSTEALiExsis (Dana). (Plate v., figs. l-lc). 



Very briefly described by Dana (1853, p. 1271) ; detailed description pub- 

 lished by Sars in 1888. 



Female. Carapace, seen laterally, rhomboidal in outline, with the length 

 greater than the height; dorsal edge slightly arched, ventral edges bulging an- 

 teriorly ; posterior prominence broad and obtuse. Head small, ventral edge nearly 

 straight. Carapace obliquely striated. Eye of moderate size, ocellus very small, 

 punctiform. Post-abdomen broad, armed with nine anal denticles which increase 

 in size distally; end-claws long, slightly curved and armed with a series of 

 spinules. Colour yellowish-brown. Length 2 mm. 



This species has a wide distribution in New South Wales, and usually occurs 

 in large numbers. 



Distribution. — N.S.W. : Clyde, Parramatta, Five Dock, University Pond, 

 P)Otany, Maroubra, Manly, Holbrook, Moss Vale, Kendall, Bangalow. Dana 

 found it in "fresh water ponds near Sydney." It also occurs in Queensland, 

 South Australia, and South Africa. 



SiMOCEPHALUS ELIZABETHAE (King). (Plate v., figs. 2-2fl.). 



Described by King (1852) as Daphnia elizabethae and more fully described 

 by Sars in 1888. 



Female. Carapace, seen laterally, irregularly oval, broadening posteriorly 

 and terminating in an obtuse median prominence which is more distinct than in 

 the preceding species. Head somewhat triangular, with the ventral edge con- 

 cave. Eye of moderate size, ocellus in the form of a black stripe running 

 obliquely towards the rostrum. Carapace obliquely striated, posterior part of 

 the dorsal edge denticulate, the denticles continuing round the posterior pro- 

 minence. Fost-abdomen with the supra-anal angle projecting and denticulate; 

 end-claws smooth ; about six anal denticles present. Colour pale brown. Length 

 1.5 mm. 



King gives the following localities in New South Wales: — Newtown, Parra- 

 matta, Stroud and 'Port Stephens, but it is possible that some of these may refer 

 to the preceding species which he did not recognise as distinct. This species is, 

 however, widely distributed throughout the State, having been collected at Cen- 

 tennial Park, University Pond, Botany, Moss Vale, Holbrook, and Mudgee. It 

 has also been recorded from Victoria, Queensland, South Australia, Sumatra, 

 Java, Siam, India, and Ceylon. 



SiMOCEPHALUS ACUTIROSTEATUS (King). (Plate v., flgs. -l-4«.). 



First mentioned by King (1852, p. 254) as a variety of the preceding 

 species, Daphnia elizabethae var. acutirostrata. In 1877 Schoedler pointed out 

 that it was specifically distinct and it was described by Sars in 1896. 



Female. Carapace, seen laterally, oval in outline; dorsal and ventral mar- 

 gins evenly curved, the latter bulging somewhat anteriorly; posterior prominence 

 obtuse, produced, situated above the longitudinal axis of the body. Head small, 

 with the front produced into an acute projection, ventral edge straight. Cara- 

 pace marked by oblique striations, posterior prominence bearing a few denticles. 

 Eye comparatively small, ocellus small, punctiform. Post-abdomen very broad; 

 the posterior edge foi-ming an expansion in front of the anal sinus; twelve anal 

 denticles present; end-claws bearing a series of spinules. Colour pale brown. 



This is by far the largest species of Simocephalm found in Australia; the 

 average length is about 3.3 mm. but specimens have been examined which were 4 

 mm., the very largest attaining the length of 4.2 mm. 



