40 TREiNIAtODES OF THE NORTHUMBERLAND COAST 



of head spines is variable. I have examined many specimens 

 and find these head spines vary from 48 to 58 in two 

 uninterrupted rows of 24 to 29 spines each. Johnstone's figure 

 of the head shows the lower spines also longer than the upper, 

 but he does not mention the fact. The oral sucker measures 

 o'26 mm. across, and has a large aperture leading to a long 

 prepharynx about 0*5 mm. long. The pharynx (o-i8 mm. 

 long) is thick, and leads to a broad oesophagus branching into 

 two rather thin intestinal lobes which reach almost to the end 

 of the body. Just below the fork of the intestine is the genital 

 aperture, which occurs immediately in front (either median or 

 to the side) of the ventral sucker (o'23-o*26 mm. across). Two 

 small round testes and an ovary lie in a row obliquely across 

 the hinder portion of the body between the ventral sucker and 

 the posterior end, but their positions are somewhat variable, 

 and sometimes they are placed almost straight behind each 

 other. The vasa deferentia are distinctly seen running to a 

 thin, somewhat club-shaped vesicula seminalis, in front of 

 which the cirrus-sac encloses a small spined cirrus. The ovary 

 has a thin duct running from it to the genital opening, but 

 none of the other female organs are yet developed. A large 

 opaque excretory vesicle occupies the posterior region, hiding 

 the testes and ovary, but by gentle pressure the contents of 

 the vesicle are set free, and these organs can be clearly seen. 



I do not think this worm is Distoimim valdeinflahtm, 

 Stossich, which, according to Monticelli*, is synonymous with 



D. bicoronatnm, Stossich, and Echinostoinum cesticillus, Molin. 



E. cesticillus is now placed in the genus Stephanochasinus, 

 Loosf, and this author recognises both S. cesticillus and S. 

 bicoi-onahun as separate species. The former has 35-36 head 

 spines, and the latter 31, the lower row of both species having 

 one spine less than the upper, thus forming a gap in the 

 centre ; and the spines of the lower row are shorter than those 

 of the upper, which is exactly the reverse in my specimens. 



'* MonticelH, "Studii sai Tvematocli eiidoparasslti," Zool. JahrV). Supp. III., 

 1893, p. 161. 



t Looi, A,, " TJeber die Fasciolideugeuera ytepliauochasmus, etc.," Centralbl. f . 

 Bakt., etc., Bd. XXIX., IPOl, p. 595. 



