TRILOBIDAE 89 



be established when much more complete descriptions are 

 available. 



a. Acmaeolaimus Filipjev, 1918. 



Cuticle thick, finely striated. Head with two crowns each 

 of six papillae, and four stout bristles. Lateral organs like 

 thick plates, with spirals within. Buccal capsule like a shallow 

 cup, its dorsal wall thickened and prolonged posteriorly. 

 Internal anatomy unknown. 



Hab. Marine. 



Genotype : A. diplopeltoides Filipjev, 1918. 



Filipjev, 1918, Trav. Lab. Zool., Stat. Biol. Sebastopol, 

 Ser. II, No. 4, 345. 



b. Symplocostoma Bastian, 1865. 



Cuticle without striations or bristles. Head not distinct, 

 with or without bristles. Lateral organs unknown. Pharjaix 

 elongate, " somewhat fiddle-shaped, having a peculiar funnel- 

 shaped body lying along its inferior aspect, and an appearance 

 of three or more circular lines around the parietes." Oesoph- 

 agus widening considerably but gradually behind, without 

 bulb. Ocelli present or absent. Caudal end of male appar- 

 ently without supplementary organs or papillae. Accessory 

 piece absent. Female genital tubes paired, opposed. Caudal 

 glands and spinneret present. 



Hab. Marine. 



Genotype : S. longicolle Bastian, 1865. 



Bastian, 1865, Trans. Linn. Soc. London, xxv, 132. 



This genus was only tentatively proposed by Bastian, and 



its validity is somewhat uncertain. 



c. Pelagonema Cobb, 1894. 



Cuticle unstriated, without bristles. Head not distinct. 

 Lateral organs inconspicuous. Pharjaix simple, elongate, 

 without teeth. Oesophagus gradually swollen in its posterior 

 half. Male unknown. Female genital organs paired, opposed, 

 reflexed. Caudal glands present. 



Hab. Marine. 



Genotype : P. simplex Cobb, 1894. 



Cobb, 1894, Proc. Linn. Soc. N.S.W., Sydney, viii, 391. 



This genus is considered by Cobb, in spite of the absence of 

 teeth, to be related to Oncholaimus. 



d. Diplohystera Onorato-de Cilhs, 1917. 



Body considerably swollen in middle region. Cuticle 

 smooth, without bristles or lateral alae. Head not distinct, 



