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I think the best plan is to begin by giving an account of the features which are 

 common to all species, subsequently describing each species separately. A tuft of hairs 

 outside the base of the maxillulae in both sexes, and the shape of the frontal border in the 

 male, are probably the most characteristic features which distinguish them from all other 

 species of the genus Sphceronella. 



FEMALE. Body ovate or sub-globular, with well-defined head. Antennulae of 

 about medium length, 3-jointed, the last joint provided with rather short setae. Frontal 

 margin naked. Antennae rudimentary (pi. Ill, fig. 2 c, c), but generally visible. The mouth 

 of middle size. Setae of the mouth-border of medium length. Maxillulae provided with an 

 additional branch; outside and somewhat behind their base a peculiar, pretty large tuft of 

 hairs turning outward. Maxillae of medium size. Maxillipeds normal, with hairy spots on 

 their basal joint. The sub-median skeleton between the rostrum and the base of the maxilli- 

 peds forms rather broad longitudinal plates, but there is no transverse list on the ventral 

 side at the posterior limit of the head. The lateral margin of the head provided with a 

 row or a stripe of moderately long hairs. Trunk-legs and caudal stylets always distinct 

 (e. g. pi. II, fig. 6 a). Genital area much narrower than the head, broader than long, plate- 

 like or only with a solid ring which has no opening in front. The curved genital apertures 

 turn their front extremity forward, their hind extremity sideways, and their distance from 

 each other is shorter than the length of each. Caudal stylets either on the posterior margin 

 of the genital area (pi. II, fig. 5 b) or, as a rule, behind or far behind it (pi. II, fig. 3 b). 



MALE. This sex is known of six of the species. The body is from one third to 

 one half longer than broad. The head about the size of the trunk. The frontal border 

 produced so as to form in advance of each antennula a pretty large, rounded, distally ciliated 

 lobe, which is separated by a deep and broad incision from the odd, long, broad and almost 

 square median plate, the sides of which are often somewhat diverging, sometimes parallel; 

 its slightly curved anterior margin, as well as the distal part of the lateral margin, are 

 furnished with fine and short hairs. Antennulae, antennae, rostrum, maxillulae, the hair-tuft 

 at their basis, maxillae and maxillipeds, chiefly as in the female. The sub-median skeleton 

 with first and second pairs of processes well developed; first pair rather prominent, triangular, 

 pointed, situated close in front of or overlapping the base of the maxillipeds; second pair 

 situated at the inner angles of the maxillipeds, elongated, extending over the basal part of 

 the trunk, and more or less diverging. Lateral margin of the head ciliated; from its posterior 

 extremity a narrow belt of long hairs extends upward over the side and in an oblique 

 direction across the back. The ventral surface, the sides and the hindmost part of the trunk 

 are covered with moderately long, posteriorly towards the back with very long hairs, leaving 

 a large naked area behind the above-mentioned transverse belt. The legs of moderate and 

 sub-equal length; the first pair consist of a peduncle, one branch, and a short conical 

 process on the outer side at the apex of the peduncle; the proximal part of the peduncle is 

 stout and rather broad ; the branch which must be homologous with the outer one in the following 



