. Bulletin - United States National Museum. Science. MARDSTE GAMMARIDEAN AMPHIPODA 171 Even the type-genus, Calliopius, has enlarged gnathopods, not typical of the remaining members of the family. Extremes of variation are shown in a group of gnathopodal figures presented herein. Apherusa, Bouvierella, Calliopiella, Halirages, and Haliragoides are often very difficult to separate. Their type-species are easily dis- tinguished by conditions of lower lip, anteroventral cephalic corners, coxa 1 and accessory flagella, but those characters are highly variable among other species of the five genera
. Bulletin - United States National Museum. Science. MARDSTE GAMMARIDEAN AMPHIPODA 171 Even the type-genus, Calliopius, has enlarged gnathopods, not typical of the remaining members of the family. Extremes of variation are shown in a group of gnathopodal figures presented herein. Apherusa, Bouvierella, Calliopiella, Halirages, and Haliragoides are often very difficult to separate. Their type-species are easily dis- tinguished by conditions of lower lip, anteroventral cephalic corners, coxa 1 and accessory flagella, but those characters are highly variable among other species of the five genera. Gurjanova (1962) has pointed out the unusual character of Sancho and Chosroes. They have broadly vaulted, extremely depressed bodies and heads and splayed coxae like those of Phliantidae but they also have subfossorial pereopods and gnathopod 1 like that of fossorial families Phoxocephalidae, Haustoriidae, and Figure 73.—-Calliopiidae: Gnathopod 2: a, Sancho platynoius Stebbing (1897); b, Clarencia chelata K. H. Barnard (1932); c, Stenopleura atlantica Stebbing (1888); d, Cleippides bicuspis Stephensen (Gurjanova, 1951); e, Atylopsis dentatus Stebbing The mouthparts of both genera have a distinct look of the Oedi- cerotidae. Neither genus has the fully developed pereopod 5 nor elongate peduncle of uropod 3 found in the Oedicerotidae and Chosroes has an elongate telson. Gnathopod 2 of Sancho distantly resembles that of the phoxocephalid Joubinella (and various eusirids); and since Phoxocephalidae and Haustoriidae seem to have strong affinities one might consider Sancho to be an aberrant member of the Haustoriidae, were it not for the uncharacteristic short peduncle of antenna 1, the large male gnathopod 2, and the shortened outer rami of the uropods. The conditions of the telson and pereopod 5 exclude the genera from the Phoxocephalidae. But the short outer rami of the uropods of Sancho and Chosroes like those of the Calliopiidae and Eusiridae are not charact
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