A NEW NEMATODE GENUS 115 



each lateral line opposite the posterior end of the oesophagus, occupying a dis- 

 tance equal to the body radius. Nothing is known concerning the sexual organs, 

 as the description is derived from a single immature specimen. 



Habitat. Found on calcareous algae, near low-tide mark, Colon, Panama; 

 where it was feeding on other nematodes. 



Selachinema seems without doubt to belong to the family Enoplidae, 

 which may now be defined as follows: Free-living, marine, carnivorous 

 nematodes with three mandibles; head armed with setae and papillae; 

 body naked; cuticle transversely striated, sometimes also obliquely 

 striated; oesophagus plain; intestine with a variety of well-developed 

 specialized cells indicating definite division of digestive functions; 

 renette and caudal glands present ; male and female sexual organs double, 

 spicula two, equal; amphids usually small, inconspicuous, oval or spiral. 



The following genera may be included in the family: 1. Demonema, 

 Cobb 2. Enoploides, Ssaweljev 3. Enoplolaimus, de Man 4. Eno- 

 plus, Dujardin type genus 5. Labyrinthostoma, Cobb 6. Selachi- 

 nema, Cobb 7. Triodontolaimus, de Man. 



The sub-family Enoplinae should contain Enoplus, Enoplolaimus, 

 Enoploides and Labyrinthostoma; the sub-family Selachineminae, Se- 

 lachinema. Demonema and Triodontolaimus probably represent dis- 

 tinct sub-families. There is probably confusion of characters in 

 Enoplolaimus, Enoploides and Labyrinthostoma, and it may become 

 necessary to rearrange the species now included under these generic 

 names. 



Enoplidae occur in all parts of the world, the following being the 

 present known geographical distribution of the various genera. 



Demonema Italy, California Labyrinthostoma Ceylon 



Enoploides . . Arctic, Massachusetts Selachinema Panama (Colon) 



Enoplolaimus Cosmopolitan Triodontolaimus .English Channel 



Enoplus Cosmopolitan 



Demonema, Enoplus and Selachinema all contain species known to 

 devour other nematodes. The granules in the intestinal cells of the 

 Enoplidae give rise to the rather distinctly tessellated appearance which 

 I have observed to be more or less characteristic of the free-living 

 nematodes which feed upon animal organisms, or at least those which 

 feed in whole, or in part, upon other nematodes. The following de- 

 scription, derived from the examination of an Enoplus whose intestine 



