8 



the stalk and two in the flagellum), of which four are long, virgate, and 

 tucked zigzag under the body, while the 5th (distal) is usually much shorter 

 than the rest, sometimes rudimentary. In the Lanceola, Scypholanceola, 

 Megalanceola, and Prolanceola, the six-eight-articled antennae II are usu- 

 ally longer than antennae I; in the remaining Physosomata they are short; 

 and in some Scinidae they may be totally lacking (Ctenoscina, Acan- 

 thoscina). Antennae II are very small and highly reduced, just one- to 

 two-articled in females of many species of the families Hyperiidae, Phron- 

 imidae, Platysceloidea, and others. In females of the Oxycephalidae, anten- 

 nae II are totally absent, and in the Cystisoma are retained in the form of 

 a spine on the lower part of the head. 



The mouthparts of hyperiideans exhibit some degree of reduction com- 

 pared to the initial "gammaridean" type. The labrum is small, sometimes 

 bilobate, frequently almost not developed. The degree of reduction of the 

 mandibles is highly variable. In the most developed type the mandibles 

 bear a powerful, three-segmented palp, a cylindrical dental process with 

 a worn surface, and the left mandible bears an accessory plate at the cut- 

 ting edge (genus Cyllopus). In the Lanceola the dental process is reduced 

 and the strong palp is retained; contrarily, in the Hyperia, Hyperoche, and 

 Parathemisto, the mandibular palp is weaker. In other genera {Hyperietta, 

 Hyperioides, Hyperionyx, lulopis, Lestrigonus, Themistella) of the same 

 family, it is present only in males and absent in females. In the Phronimidae 

 the powerful dental process is retained, but the palp is reduced in both sexes. 

 In many genera from different hyperiidean groups the mandibles lose both 

 the palp and the dental process but retain the comparatively well-developed 

 cutting edge and the accessory plate (Mimonectes, Proscina, Mimoscina, 

 Chuneola, Anapronoe, Paraphronima). In the Scina and Acanthoscina the 

 mandibles are the most reduced and retain just a short, denticulate cutting 

 edge without the accessory plate. 



Maxillae I are also reduced to a variable extent. They may be 

 well developed, with distinct and armed inner and outer lobes, and 

 well-developed but always one- segmented palp {Lanceola, Scypholance- 

 ola, Mimonecteola, proscina). Different-parts of the maxillae are also 

 reduced: the palp is shortened (Matalanceola, Bougisia), modified into 

 a small protuberance with an apical seta (Acanthoscina), or disappears 

 altogether (Hyperoche). In many groups the inner lobe is totally reduced, 

 while in others the outer lobe is sharply reduced (Acanthoscina, Bougisia, 

 Dairella); finally, maxillae I may be modified into small round plates 

 (Hyperoche). 



In most hyperiideans maxillae II do not have fused outer and inner 

 lobes and are armed with one strong apical spine each. However, in 

 some highly specialized groups, the two lobes are fused, forming a single 

 weakly armed plate. 



