334 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



sucker (os) wider than long; 0.153 to 0.204 mm. in transverse 

 diameter; 0.153 to 0.197 mm. in depth (dorso ventral) . Dorsal wall 

 of oral sucker much thicker than ventral wall ; a small papillalike 

 projection often visible on midventral line. Acetabulum, including 

 aperture, slightly wider than long; 0.157 to 0,219 mm. in trans- 

 verse diameter or subequal to oral sucker; sucker ratio 1:0.85 to 

 1.04. Depth of acetabulum, as seen from side view, 0.124 to 0.146 

 mm. or somewhat less than depth of oral sucker. Forebody 0.299 to 

 0.431 mm. 



Prepharynx very short; pharynx (ph) globular, 0.043 to 0.076 

 mm. long by 0.048 to 0.068 mm. wide by 0.051 to 0.059 mm. thick. 

 Esophagus (e) not clearly demarked from cecum; cecum (ic) ex- 

 tending to a point one-fourth to two-thirds distance from acetab- 

 ulum to posterior end of body, usually ending dorsal to testis. 



Genital pore median, slightly nearer to oral sucker than to 

 acetabulum, opposite posterior edge of pharynx or slightly pos- 

 terior to that level. Single testis (t) , elongated oval, 0.182 to 0.277 

 mm. long by 0.116 to 0.138 mm. wide, smooth; located usually 

 somewhat anterior to middle of hindbody ; posttesticular space very 

 long, 0.292 to 0.474 mm., in only one specimen was it shorter than 

 the forebody. Cirrus a thick-walled tube extending diagonally 

 backward from genital pore, sometimes appearing spherical from 

 surface view; prostatic vesicle (pv) ovoid to elongate, not appar- 

 ent in many specimens; seminal vesicle (sv) a slightly sinuous 

 tube ending dorsal to acetabulum; entering ventral side of pros- 

 tatic vesicle slightly posterior to its middle. 



Ovary (ov) spherical or ovoid, immediately posterior to acetab- 

 ulum or partly dorsal to acetabulum, pretesticular, median or 

 submedian, usually slightly dextral. Seminal receptacle spherical 

 or ovoid, largely dorsal and slightly posterior to ovary. Vitelline 

 glands (v) not in definite follicles but in irregular longitudinal 

 masses, lateral, usually from level of pharynx to well posterior 

 to testis; always interrupted opposite testis. Anterior extent of 

 vitellaria seems to be the anterior border of acetabulum although 

 large cells in the forebody probably are vitelline cells ; the posterior 

 extent varies from one-half to four-fifths distance between testis 

 and posterior end of body. Uterus preovarian, short, dorsal to left 

 half of acetabulum. Eggs (fig. 18) large, few (1 to 7), measuring 

 (uncollapsed) 73 to 80/a by 48 to 53 fi. Excretory vesicle forking 

 dorsal to testis. 



Host. — Girella nigricans (Ayres), common opaleye. 



Location. — Intestine. 



Number. — Very numerous. 



Tijves. — Holotype and paratype, U.S.N.M. Helm. Coll. No. 37144. 



Discussion. — Of the eight known species of Haplosplanchnus, H. 



