8 LaiDLAW, Marine Turbdlaria from Torres Straits. 



striking resemblance between the genital apparatus of 

 the two genera Latocestiis and Acelis, which she refers re- 

 spectively to the families Cestoplanidae and Leptoplanidae. 

 I believe that the resemblances are strong enough to 

 outweigh the striking external differences in shape, etc., 

 and indicate a connection between the two genera. The 

 possession of a pair of vesiculae seminales is exceptional 

 in the Leptoplanidae and the typical Cestoplana have only 

 one. Further, I do not know of any Leptoplanid in 

 which the prostate gland is segmented off so distinctly 

 from the sperm duct, whilst in Cestoplana the prostate 

 cells line part of the lumen of the duct. In fact, I believe 

 that the relationship between Cestoplana and certain 

 Leptoplanids is distinctly closer than between Cestoplana 

 and Latocestiis. Accordingly, I propose to constitute an 

 independent family to receive these two genera, Latocestis 

 and A cells. 



Latocestus PACIFICUS, Sp. n. 

 Two specimens, both immature, from Rotuma. An 

 interesting new species, very distinct from L. atlanticus, 

 the only member of the genus hitherto described. 

 Unfortunately, the gonads are undeveloped, and it is 

 consequently impossible to ascertain whether the same 

 peculiarity obtains with regard to the position of the 

 testes that was noticed by von Plehn [4] in L. atlanticus. 

 The terminal parts of the ducts are sufficiently 

 developed to show that this species is closely allied to 

 L. atlanticus. 



Total length about - - 12 mm.? 



„ breadth „ - - 2-5 „ 



Brain from anterior margin - 4 „ 

 The mouth opening and sexual apertures lie close to 

 the hinder end of the body. The anterior margin of the 



