AMPHIPODA. 



503 



Tribe 2. HYPERINA NORMALIA. 



Both antennae arise from the frontal surface of the head ; the posterior 

 is not folded in the male, in the female it is often absent or vestigial. 

 The sixth and seventh thoracic legs present various modifications in size 

 and shape. 



Fam. 1. Phronimidae. Head large, often produced downwards. 

 Eyes divided into dorsal, " frontal " and lateral regions, the ommatidia 

 of the former being greatly elongated ; they occupying the greater part 

 of the head. Both antennae long in the male, each with a many -jointed 

 flagellum ; the first is short and without flagellum in the female, and the 

 2nd vestigial. The liver tubes are rudimentary. 



Sub-fam. 1. Phrosininae. Body short, compressed, the three 

 hinder pairs of abdominal feet broad and fin-like. Anchylomera M. 

 Edw. ; Phrosina Risso : Primno Guer. 



Sub-fam. 2. Phroniminae. Elongated, the last thoracic segment 

 long. Three hinder abdominal feet narrow. Phronima Latr. P. 

 sedentaria Forsk. (Fig. 307) is a widely distributed species. Perfectly 

 transparent, except for the retinal pigment of the eyes (it is absent 

 from the iris cells) .and a few purple pigment cells on the limbs. 

 Chun concludes that Phronima and its allies live, except in the 

 breeding season, in the dark deeper regions (300-600 fms.) of the 

 ocean. At that season the females approach the surface and take 

 possession of the gelatinous test of a Pyrosoma or Salp, or the 

 nectocalyx of a Siphonophoran, the protoplasmic portions of the 

 owner being consumed by her. (Phronima is known as " Napoli- 

 tano " by the fishermen of Messina.) The males arrive at the 

 surface later, and the brood when it leaves the brood pouch is shel- 

 tered in the test. After the breeding season the males probably die, 

 and the female and the young descend to deep water. Phronimella, 

 Phronimopsis and Paraphronima Glaus. (?) Tryphana Boeck. 

 Fam. 2. Hyperiidae. Head large and rounded. Eyes large. Both 

 antennae are present .in both sexes. "Liver tubes well developed. 

 Themisto Guer. T. arctica Kroy. attains a length of 60 mm. It is found 

 at the surface and in deep water of arctic seas. Cyllopus Dana ; Cys- 

 tosoma Guer. C. neptuni, 84mm. long, from the deep sea (1,090 fathoms) ; 

 Tyro M. Edw. ; Hyperia Latr. : Daira M. Edw. ; Mimonectes Bovallius ; 

 Lanceola Say. 



Fam. 3. Vibilidae. Head small, truncated in front. Eyes small. 

 Both antennae present, the first the stouter. Shape of the body like that 

 of a Gammarid. Vibilia M. Edw. V. Jeangerardi Luc. commensal in 

 Salpa democratica, Mediterranean. 



Sub-order 2. LAEMODIPODA. 



The first and second thoracic segments are fused with the head to 

 form a cephalo-thorax. Abdomen reduced to a stump-like process 

 of the thorax. Second and third free thoracic segments with paired 

 saccular branchiae, but usually without legs. 



Fam. 1. Caprellina (Fig. 308). Grotesque Crustacea with long and 

 very attenuated bodies ending abruptly with the stump -like abdomen, and 



