AFFINITIES - 461 



from a sandy bottom at a depth of 10 to 20 fathoms off the Philippines. 

 Its tube is covered with particles of sand, sponge spicules, etc. Its length 

 is 52 mm. or more (more than two inches). The anatomy of this species 

 closely resembles that of Ph. australis, and Benham thinks that, in spite of 

 the difference in their habitat, they may belong to the same species. 



(v.) Phoronis architecta Andrews. A species recently described by 

 Andrews from Beaufort, N.C. Its distinctive features are : " the formation 

 of isolated tubes covered by definite collections of sand grains ; the presence 

 of special prostomial organs, possibly of use in the formation of these tubes ; 

 the great development of the longitudinal muscles ; the presence of a ciliated 

 groove in the digestive tract ; the apparent separation of the sexes." 



(vi.) Phoronis psammophila Cori. Found in Faro, near Messina. The 

 tube is hyaline, and is covered by numerous grains of sand, some of consider- 

 able size. The length of the individuals is 25 to 50 mm. There are 60 to 

 90 tentacles. The colour is a fleshy red. A second species discovered by 

 Haswell in Port Jackson had no points of importance to distinguish it 

 from Ph. psammophila, except that no sand adheres to its tube and the 

 number of tentacles is slightly greater. 



In addition to the various species of Phoronis, several distinct forms of 

 its larva, Actinotrocha, are known, and have been named without having 

 been traced into their corresponding adult form. 



The position of Phoronis in the animal kingdom has formed 

 the matter of considerable divergence of opinion amongst the 

 naturalists who have studied it. The earlier writers regarded 

 Phoronis as allied to the Gephyrea, and it was for a long time 

 classed with these animals, but placed in a separate sub- Order, 

 the Gephyrea tubicola, which was opposed to the Gephyrea nuda, 

 which comprised the true Gephyrea. 



Caldwell referred Phoronis, the Brachiopoda, the Polyzoa, 

 and the Gephyrea to the same type of body structure, and 

 Lankester subsequently suggested the provisional name Podaxonia 

 for this miscellaneous collection of animals. Lankester divided 

 his phylum Podaxonia into three classes : (i.) the Sipunculoidea 

 (Gephyrea), (ii.) the Brachiopoda, and (iii.) the Polyzoa. The 

 last-named class he divided into three sections : (a) the Vermi- 

 formia, this includes the single genus Phoronis; (b) the Ptero- 

 branchia, including the forms Cephalodiscus and Ehabdopleura, 

 whose affinities with Balanoglossus were subsequently demon- 

 strated ; and (c) the Eupolyzoa, including the forms treated as 

 Polyzoa in the following pages. 



Masterman's recent researches 1 on Phoronis seem to indicate 

 1 Proc. Roy. Soc. Edinb. vol. xxi. 1896, p. 59 ; and Zool Anz. xix. 1896, p. 266. 



