ii FAMILIES OF CLADOCERA 53 



Fam. 4. Bosminidae : feet equidistant, five or six pairs ; the first 

 antennae of the female immobile, with sense-hairs arranged in rings, 

 not forming an apical tuft.. The intestine uncoiled ; no caeca. 

 Bosmina, Baird (Fig. 22). 



Fam. 5. Lyncodaphniidae : four, five, or six pairs of equidistant thoracic 

 limbs ; the first two pairs prehensile. First antennae of female 

 mobile, with apical sense-hairs. Intestine coiled or straight, 

 i. Four pairs of thoracic limbs. Ltithonura, Lilljeborg. 

 ii. Five pairs of thoracic limbs. 



a. The four-jointed ramus of the second antenna with four 



swimming hairs. Macrothrix, Baird : the first antennae 

 of the female flattened, curved. The intestine simple, 

 straight. Streblocerus, Sars : first antennae of the female 

 very little flattened, curved 1 uickwards and outwards. The 

 intestine coiled, the stomach with two foiwardly-directed 

 caeca. 



b. The four-jointed ramus of the second antenna with only 



three swimming hairs. Drepanothrix, Sars. 



iii. Six pairs of thoracic limbs ; the labrum provided with an 

 appendage. Acantholeberis, Lilljeborg: appendage of labrum 

 long, pointed, and setose. Intestine without caecum. 

 Ilyocnjptiis, Sars : appendage of the labrum short, truncated. 

 Intestine with a caecum. 



B. Both rami of second antenna three-jointed. 



Fam. 6. Lynceidae 1 : five or six equidistant pairs of thoracic feet. 

 Intestine coiled. 



i. Six pairs of thoracic limbs. Head and thorax separated by a 

 deep depression. Intestine with one caecum, stomach with 

 t\vo. Female carries many summer - eggs. Em-iif>'rcus, 

 Baird. 



ii. Five pairs of thoracic limbs. Head and thorax separated by a 

 slight groove or not at all. Anterior digestive caeca absent. 

 Female carries only one or two summer-eggs. 

 A. I'.ody elongate, oval. 



a. Head carinate, the eye far from the anterior cephalic, margin. 

 Cam/if"" mis, Baird: body laterally compressed. Second 

 antennae with seven swimming hairs. Tel. -on m<>iv than half 

 as long as the shell. vlo-</y;<r/>s, I'.aird (Fig. 23): bod\ 

 compressed. Second antennae with eight swimming hairs, of 

 which one is very small. Tel.-nn le.-s than half a- long as 



the shell. 



b. Head not carinate, the eye near the anterior cephalic mar-in. 

 Alonopxix, Sars : terminal cla\\s of tel.-on with thre( accessor] 

 teeth. Ahum, Baird: terminal claw.- of lelson wiih one 

 accessory tooth (includes .-ub-geiiera /,W/Vc. .I/"/"', //-'///'/- 

 rhynchus^Graptoleberis). 1'i-rm-n iirim, 1 laird (Fig. 14): terminal 



1 More properly Chydoridae,! mt the universally known nanu- Lynceidac i 

 venient. 



