Entozoa of British Murinf. Fishex. 83 



in the posterior. lu Sfejjfi. mlnulus, Looss*, tlicy are of 

 equal size ia the two rows, Ijut in the otlar species the 

 auterior row contains the hirgcr spines. In addition the 

 ova are mucli hirger than those of any other species e.vcept 

 Siejj/t. cfslicillus. 



Zuo(/onoides vivij/anis, Olsson. 

 (PI.' II. fit?. 8 ; PI. III. fig. 9.) 



Diatomum vivipnnon, Olsson, Ltiuds Univ. Arsskrift, 1867, iv. no. 8, 



p. 28, pi. iv. tigj«. 73-75. 

 Zooffunim vivi/iantu, Loos«, Ceutralbl. B.ikt. Iste Abtlieil. xxi.t. p. 440. 

 Zoo</onoides rivijnirus, Odliner, C'eiitrrtlbl. Hakt. Iste .Vljlheii. x.xxi. 



p. e-2, fi-. -2. 



This spceits, first discovered hy Olsson in Pleuronedes 

 microcephalus and incorrectly described by hini, has been 

 fully described by Odhncr. Looss assigned it to the genus 

 Zoof/onus, Lss., along with Z. inirus, Lss., but Odhner with 

 reason regarded it as the type of a new genus. Olsson was 

 only able to discover two specimens, occurring, as he believed, 

 in the stomach of the host. Odhner, however, correctly 

 points out that the true habitat of the species is the terminal 

 portion of the intestine. He found it in Pleuronedes Jiesus, 

 PI. limanda, PL platessa, PL microcepholus, Jlippoglossoides 

 platesso'ides, and Calliony/nus lyra. I have found it here in 

 PL liinanda, PL p/alcssa, and Rhombus maximus, and 

 always in the lower reaches of the intestine, particularly the 

 rectum. It always occurs in lai'ge numbers, usually accom- 

 panied in Pleurunecti's limanda by Steringophorus furciger, 

 Ol-son. 



Odhner's description of the species is almost exhaustive. 

 The limits of size which he gives, however, are rather 

 narrow. I have found mature examples as small as '8 mm. 

 and, in Rhombus ma.rhnus, as large as TG mm. ; in Pleuro- 

 nedes limanda they never exceed 1'2 mm. The maximum 

 breadth is •31-42 mm. The diameter of the oral sucker 

 lies within Odhner's limits, viz. "H-'IG mm.-, but the ventral 

 sucker is never twice as large, as Odhner has it, and its 

 ajicrturc is nearly circular, or if elliptical the eccentricity is 

 small. The cuticular spines are very minute, arranged in a 

 regular diamoufl pattern, and cover the whole body except 

 a small part at the posterior end. The intestinal diverticula 

 do not extend beyond the posterior border of the ventral 

 sucker. 



The testes are two ovoid bodies, situated about the level 



• Centralbl. fiir Bakter. Iste Abtheil. ixix. p. 604, fi;:8. 5, ba. 



