ART. 26 FOUR NEW TEEMATODE WORMS MacCALLUM 5 



On attempting to compare it with the other forms described, we 

 find that this worm differs in some respects from all. It is much 

 smaller than JS. borealis, which measures 20 mm. in length, and has 

 not the large open mouth sucker shown in that species. It is closer 

 to /S. vidgans, except that that species also has a large bell-shaped 

 mouth sucker, vaginal orifices near the margin of the body, and eggs 

 measuring 200/x in length with straight prolongations. In other re- 

 spects it resembles this form, but has no tubercles in the cuticle about 

 the orifice of the mouth sucker. It differs from S. cants in that the 

 eggs of that form have two very long, fine filaments, and this too 

 applies to 8. dbhremata. From 8. grisea^ too, it differs, especially in 

 the size of the eggs, which are there only lT5/x long, while in the 

 present form they measure 320^1* by 120jli. 



It seems necessary therefore to separate this as a new species, 

 ^iS". squali^ with the following characteristics : Parasite of gills of 

 Squalus acanthias; 7 to 10 mm. in length ; small mouth sucker ; simple 

 intestinal prolongation in fixation disk; vaginae separate to vitelline 

 duct; ribbed ootype; eggs with recurved filament at each end. 



Type specimen. — U.S.N.M. Helm. Coll. No. 8133; paratypes, 

 No. 8134. 



SQUALONCHOCOTYLE ACANTHI, new species 



Plate 1, Figube 3 



Specific diagnosis. — Squalonchocotyle : This form, also found on 

 the gills of Squalus acanthias, differs from S. squali in several partic- 

 ulars although resembling it in some. It measures 5 mm. in length 

 by 0.8 mm. in breadth. The mouth sucker is small with no flowing 

 margin, the pharynx small, and the intestinal ceca simple with a 

 simple prolongation into the disk. The sucker hooks measure 240/a 

 from tip to tip (fig. 1, h). The small booklets in the appendix (fig. 

 1, h') are very narrow and delicate, with long, sharply recurved 

 points, and are quite different, therefore, from those of S. squali. 



In the available specimens it is impossible to make out the position 

 of the vaginal orifices or the course of the vaginae. The ovary is 

 small and round, without lobulation. The uterus is thin-walled and 

 straight without any distinct ootype. Two eggs were found in one 

 specimen, and these measured 304/^ by 96|a and may be seen to have 

 a short recurved filament at each end. The genital opening is un- 

 armed and lies just behind the bifurcation of the intestine. 



The peculiar characters of this form are summarized as follows: 

 Parasite on gills of Squalus acanthias; measurements, 5 mm. by 0.8 

 mm. ; small mouth sucker ; uterus without ribbed ootype ; booklets in 

 appendix extremely narrow. 



Type specimen.— U.S.^.M. Helm. Coll. No. 8135. 



