6 
SYSTEMATIC ACCOUNTS 
Subgenus Simocephalus s. str. 
TYPE SPECIES. Simocephalus vetulus (O.F. Miller, 1776) 
DIAGNOSIS. Both sexes. Frons rounded, without denticles (Fig. 18). 
Head shield without depression. Head pores present (Fig. 5). Inser- 
tion of antennules at base of rostrum. Antennule short in 
correspondence with short rostrum, with neitherridges nor denticles 
on inner side (Fig. 6B,C). Aesthetes longer than base of antennule. 
Postabdominal claws without spines (Fig. 12D,E). Inner and outer 
side of claw with fine setules. Anal bay of postabdomen narrow, 
rounded, with anal teeth (Fig. 12A). 

Fig.5 S$. vetulus. Head shield. HP — head pores. 

M.J. ORLOVA-BIENKOWSKAJA 
Female. Dorso-posterior valve angle rounded or with rounded 
prominence. Valves without dorsal keel. Posterior corner of 
ephippium without protuberance (Fig. 3C). Ocellus elongate (ex- 
ception: S. punctatus). Setae of 2nd and 3rd endite prominence of 
2nd trunk limb as long as 0.3 and 0.2 of basal segment of plumose 
seta of lst prominence respectively (Fig. 9B). Postabdomen with 
10-15 anal teeth on each side. Supra-anal angle rounded (Fig. 12A). 
Male. Supra-anal angle pointed (Fig. 14). Vas deferens opening 
there. Postabdomen with 5-8 anal teeth on each side. Dorso-poste- 
rior valve angle rounded or with small rounded prominence (Fig. 
3A). Males of the following species have been examined: S. vetulus, 
S. mixtus, S. vetuloides, S. punctatus, S. elizabethae. They do not 
differ from each other, so only females are described. 
REMARKS. Fig. 19A gives the cluster analysis of sixteen series 
(each consisting of twenty specimens) from sixteen European 
