ANATOMICAL DESCRIPTION. 



Class POLYZOA, J. V. Thompson. 



Section Vermifoemia, E. R. Laukester. 



Genus Phoronis, Strethill Wright. 



Phoronis buskii, M'Intosh. 



Phoronis sp., M'Intosh, Proc. Roy. Sec, Edin., vol. xi. pp. 211-217, May 1881. 



Amongst the peculiar forms confounded with the Annelida was a large Phoronis 

 (PL I. fig. 1), which in outline somewhat resembled an example of the Sabellid^ or 

 Eriographididee. The size of this species, indeed, had apparently led to its being over- 

 looked, for Dr. R. von AVillemoes-Suhm observes : " We have been particularly looking 

 out for Phoronis, but have never been able to find it, and feel now nearly sure that it 

 does not inhabit, as a rule, the great depths." ' At the request of the late Sir Wy\'ille 

 Thomson I undertook its description, and a preliminary account appeared in 1881. 

 The specimens were dredged at Station 212, south of the Philippine Islands, on the 

 30th January 1875, lat. 6° 54' N., long. 122° 18' E., at a depth var)dng from ten to 

 twenty fathoms, on a sandy bottom. The surface temperature was 83°. 



Distribution. — Though the genus was thus rarely met with in the Expedition of 

 H.M.S. Challenger, there is no special reason why it should be so uncommon. In our 

 own country, for instance, since its discovery by Dr. Strethill Wright simultaneously 

 at Tenby and in the Firth of Forth, it has been found by Professor KoUiker at Millport 

 in Cumbrae, by Dr. Dyster again at Tenby, and by E. Claparede in the Clyde 

 district. The larval stages (Actinotrocha) have frequently been met with off the Firth 

 of Forth ,^ at the mouth of the Mersey, and other parts. 



Tube. 



The species forms a somewhat tough hyaline and often semi-translucent tube 

 (evidently a secretion of the glandular hypoderm) for itself in the sand — as in other 

 forms having a similar habitat. In section this tube is finely and concentrically 

 striated, — layer upon layer of the hj^podermic secretion entering into its composition. 

 Moreover, even the most translucent portions show many minute sponge-spicules, 

 diatoms, fragments of silex or accumulations of coar.ser sand-grains — all more or less 



> Proc. Roy. Soc, vol. xxiv. p. 573, March 16, 1876. 



^ See Nature, vol. xxxiv. pp. 861, 387, 430, and 4G8, 1886. 



