Helminth Fauna of the Dry Tortugas. 79 



Dimensions, life, flattened: Length 0.96; breadth, anterior 0.22, 

 middle 0.36, posterior 0.08; oral sucker, length 0.15, breadth 0.14; 

 genital sucker 0.07; ova 0.017 by o.oio. Another: Length i; breadth 

 0.23; oral sucker 0.27; pharynx 0.03; genital sucker 0.07; ova 0.014 by 



O.OIO. 



Host, Hcemulon sciurus: July 4, 1907, 4 fish, i trematode. 

 Dimensions in balsam: Length 0.51; breadth 0.32; oral sucker, 

 length 0.17, breadth o.ii ; genital sucker 0.09; ova 0.017 ^Y o-oio. 



GASTEROSTOMID^. 

 Gasterostomum sp. (Figs. 219-221.) 



This species is probably G. gracilescens Rudolphi, or near it. 



The one specimen here noted proved to be so far advanced in the 

 production of eggs that details of structure can not be made out. The 

 body is blunt at the anterior end, where it terminates in a sucker which 

 is but little narrower than the body. The anterior two-thirds is linear. 

 At the anterior end of the cirrus-pouch the body begins to grow narrower 

 and tapers thence to the posterior end. The vitellaria are lateral and 

 occupy about the middle third of the length. They are compact, but 

 are not in distinct, rounded masses of definite number, as is usually the 

 case in this genus. The body is filled with ova from the posterior end to 

 the anterior sucker. 



Host, Lycodontis moringa: July 7, 1907, i fish, i trematode. 



Dimensions, life: Length 1.61; breadth 0.57; anterior sucker 0.35; 

 ova 0.027 by 0.017. 



In balsam the length is 0.7, breadth 0.4, diameter of anterior sucker 

 0.3, and diameter of ventral sucker 0.06. 



Gasterostomum sp. (Figs. 222, 222 a.) 



Body linear, anterior end truncate; anterior sucker about as broad 

 as the anterior end of the body. Ventral sucker about middle of length; 

 intestine oblong-elliptical. Testes equal, near median line, one in front 

 and the other behind the ventral sucker and very near it. Ovary be- 

 hind posterior testis, adjacent to it and a little to the right of the median 

 line. The vitellaria are irregularly rounded masses, lateral and extend- 

 ing, from about the anterior end of the intestine, half-way to the anterior 

 end of the body. Details of the structure of the cirrus-pouch could not 

 be made out. The folds of the uterus lie between the ventral sucker 

 and posterior end. The ova vary considerably in size and shape. 



The species represented by this lot is nearer G. baculum than are 

 those from Mycteroperca venenosa. 



Host, Mycteroperca honaci: July 11, 1906, i fish, numerous trem- 

 atodes. 



Dimensions, life: Length 2.52; breadth, anterior 0.21, middle 0.35, 

 posterior 0.17; anterior sucker 0.17; ventral sucker 0.056; ova 0.034 

 by 0.024. 



Other ova, in balsam: 0.034 by 0.020, 0.027 b\' 0.024, 0.027 by 

 0.020. 



