2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 9I 



testicular. Ootype oval, median, immediately anterior to ovary. 

 Vagina short, opening near inner limit of left cecum about 57 fi 

 posterior to level of base of pharynx. 



Host. — Naiicrates ductor (Linn.). 



Location. — Gills. 



Distribution. — Station 86 (lat. i9°3o'3o" N., long. 65°i4'oo" W.). 



Type Specimen. — U.S.N.M. Helm. Coll. no. 8804; paratype no. 

 8805. 



The above description is based on two specimens, both of which 

 were immature. 



Parona and Perugia (1895) described a monogenetic trematode, 

 Placunella vallei, collected in 1894 by A. Valle from Naucrates ductor 

 at Trieste, which may be the same species as that described here as 

 Ancyrocotyle bartschi. Their description of P. vallei was incomplete 

 and except for the relative size and distribution of the large hooks 

 of the posterior haptor might apply equally well to a number of 

 species of the related genus Benedenia. Later Parona and Monticelli 

 (1903) redescribed P. vallei and made it the type cf the genus 

 Ancyrocotyle ; the redescription was based apparently on the original 

 specimens. Parts of their description check well with that of A. bart- 

 schi, but in other respects there are notable differences. In the 

 redescription only two pairs of hooks are reported, but in their dis- 

 cussion it was stated that they were unable to find the others, sug- 

 gesting that they might have become lost. They also described and 

 showed in their illustrations only a single, preovarial testis ; however, 

 as the specimens were old and not in good condition, it is conceivable 

 that an error was made in interpreting the various structures. The 

 presence of a single preovarial testis, assuming that no mistake was 

 made, distinguishes A. bartschi from A. vallei. There is a difference 

 also in the morphology of the hooks of the second pair, but more 

 material is required before it can definitely be stated that this dif- 

 ference is valid. 



Family DACTYLOGYRIDAE 



Subfamily Tetraonchinae 



ANCYROCEPHALUS ATHERINAE, n. sp. 



Plate I, figs. 3, 4 



Description. — Body more or less fusiform in outline, 325 fx long by 

 95 [X wide, anterior end more attenuated than posterior end. Cephalic 

 glands few in number, lying on each side near posterior end of 

 pharynx, and opening to exterior through three pairs of prominent 



