128 U.S. NATIONAL MUSEUM BULLETIN 271 



Ampeliscidae 



Figures 57, 58 



Diagnosis. — Accessory flagellum absent; pereopod 5 shorter than 

 and of different structure from 4; article 4 of pereopods 1-2 elongate; 

 head elongate; eyes when present bearing maximum of two pairs of 

 anterolateral cuticular lenses; urosomites 2-3 coalesced; pereopods 1-2 

 glandular. See Atylidae, Haustoriidae, Argissidae. 



Description. — Accessory flagellum absent; head elongate, tall, 

 compressed; body lacking dorsal processes, except on pleonite 4 and 

 occasionally low carinae on pleonites 1-3; antennae and their pe- 

 duncles elongate, often with long setae, male primary flagellum conjoint 

 basally ; anterior coxae long, coxa 1 often broader than 2, 2 occasionally 

 tapering; mouthparts basic but mandibular palp article 3 of many 

 species much shorter than article 2 and mandibular lobes of lower lip 

 obsolescent; gnathopods feeble, subch elate or nearly simple; article 4 of 

 pereopods 1-2 elongate; pereopod 5 always shorter and of different 

 morphology from pereopod 4; pereopods with a few elongate setae, 

 especially on article 2 of pereopod 5 and article 4 of pereopods 1-2, 

 pereopods 3-4 often with strong submarginal spines on articles 4-5; 

 rami of uropod 3 lanceolate, usually elongate, occasionally foliaceous 

 or shortened; telson either elongate or very short, usually cleft, cleft 

 often short. 



Relationship. — The shiny cuticular lenses of oculate ampeliscids 

 are unique to this family, except for their rare occurrence in a few 

 lysianassids. Oculate ampeliscids also have bright red, brown, or black 

 pigmentary masses in the head towards which, perhaps, the cuticular 

 lenses direct light. 



Pereopods of this family are definitively fossorial but presumably 

 they are used not in digging but in clinging to or rearranging the 

 insides of their tubes spun by pereopods 1-2 or in creating water 

 currents and feeding. 



The Phoxocephalidae always bear a rostrum and a multiarticulate 

 accessory flagellum. The Haustoriidae bear a multiarticulate accessory 

 flagellum. Both of those families form burrows in sediments whereas 

 Ampeliscidae are provided with glands in the pereopods for the 

 construction of tubes lying on the substrate surface. 



The Atylidae have ommatidial eyes and pereopod 5 is usually 

 longer than pereopod 4 and of similar structure; the pereopods are 

 not glandular. 



