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PEOCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 88 



which the length and breadth of the pharynx were about the same. 

 In the others the breadth was greater than the length, the average 

 for 2 specimens being: Length, 0.79 mm.; breadth, 1.03 mm. 



The diameter of the posterior sucker is exclusive of the frilled 

 border, which is somewhat evanescent. The anterior suckers are more 

 or less crumpled, and the breadth could not be measured satisfac- 

 torily. The posterior sucker is usually nearly circular. 



I have a record in my notes of the finding of what was thought 

 to be this species on two occasions on the gills of the spearfish 

 {Istiophorus americanus) : 



Several specimens collected on August 17, 1913, by Dr. MacCallum. 



Three collected on July 23, 1924. The largest measured 10 mm. in 

 length and 6.5 mm. in breadth; the smallest, length 8 mm,, breadth 

 6.5 mm.; diameter of posterior sucker, 3.5 mm.; margins crenulate, 

 dorsal surface with numerous small papillae ; color translucent white. 

 These specimens were turned over to Dr. MacCallum. 



Table 2. — Measurements of six specimens of Tristoma papillosum in balsam 



TRISTOMA COCCINEUM Cavier 



Plate 14, Figuees 17.5-179 



Associated with the tristomes from the gills of the swordfish 

 {Xiphias gladius) in the collection, referred to T. papillosmn, there 

 are two specimens that differ from the others, particularly in the 

 absence of papillae and in the number and character of the spines 

 on the lateral margins. 



The marginal spines are arranged in linear groups at right angles 

 to the margins, each group containing about four spines, and there 

 are approximately 300 groups of spines on one lateral margin (pi. 14, 

 fig. 175). Each spine is flattened, longer than broad, its free end 

 bearing about five short, slender teeth. The length and breadth of 

 the pharynx are about equal. In one of the specimens there was a 

 slight constriction at about the middle of the length of the pharynx. 

 The anterior suckers and the anterior border are crumpled so that 

 exact outlines cannot be made out. There is a shallow emargination 

 at the posterior end. Measurements in balsam: Length, 12.5 mm.; 



