New Zealand Nematodes. 369 



one thousand somewhat spherical eggs, measuring 50 to 60 micro- 

 millimetres in their greatest diameter, each egg being therefore 

 one-fifth as wide as the body. 



No males were found in the collection. 



Habitat, Lakes Taupo and Waikaremoana, New Zealand, at a 

 depth of 370 to 840 feet. 



Mononchus reoc, n. sp. 



2- 6- 20- '58-' 27 81- 

 1-6 1-7 2- 22 1-4 



6*5 to 7" mm. 



is the formula of an adult female. The skin is without hairs and 

 there are no striae to be seen with moderate powers. As usual 

 the neck is cylindroid and ends in a head destitute of setae, 

 though there are papillae. These latter are low, broad and incon- 

 spicuous. While the lips do not project, the region is elevated 

 enough to give the front of the head a rounded appearance. The 

 lips are bulky and powerful, being one-third as thick as the 

 pharynx is wide. There are no eyes, and no lateral organs were 

 seen. 



The pharynx is armed with very powerful muscles that can be 

 easily seen passing from the lips to the region near the anterior 

 end of the oesophagus. The teeth are less well developed than in 

 some other species of the genus. There is a dorsal tooth, small in 

 comparison with the size of the pharynx, and reaching not more 

 than one-third the way to the lips. There are also ventrally sub- 

 median teeth located opposite the dorsal tooth, but they are 

 smaller, and one of them is seen only with difficulty in the speci- 

 mens before me. 



The oesophagus is cylindroid and is surrounded rather squarely 

 by the nerve ring, which, as is usual in this genus, is situated well 

 forward. 



The intestine is dark in colour and is about one-half as wide 

 as the body, the cells showing a tessellated arrangement of their 

 contents. The rectum is shorter than the body diameter. No 

 ventral gland or porus excretorius was seen. 



The lateral fields are one-fifth as wide as the body. 



The conoid tail tapers more rapidly at first, being nearly 

 cylindroid in the posterior two-thirds. The terminus is slightly 

 expanded, the usual spinneret being accompanied by two ventrally 

 sub-median papillae after the manner of the species longicaudatus, 

 except that here the papillae are slightly larger in proportion. 

 Three caudal glands are present. 



Two uteri lead from the inconspicuous vulva, one forward and 

 the other backward. Each uterus is capable of carrying a single 

 egg at a time, or possibly two. The eggs are nearly a fourth of a 



