252 MR. F. D. DYSTER ON PHORONIS HIPPOCREPIA. 



situated as in the Polyzoa, in lines, and not (as in many tubicular Annelids) all over the 

 surface. They exhibit no trace of thread cells, and do not appear to be used as organs of 

 prehension, but provide the food required by tlie worm by the current produced by the 

 cilia. The body is not ciliated externally. Below and between the rami of the lophophore 

 are two somewhat sigmoid ridges, which are the terminations of the oviducts. In some 

 individuals, and always in large ovigerous specimens, at the posterior inner margin of the 

 concavity of the lophophore, are seen two nearly circular Ups, apparently with a perfora- 

 tion in then- centre. Their use I cannot indicate. They may possibly be the terminations 

 of the sperm-ducts ; but as when the worm is in a position to exhibit the protrusion of 

 the ova, these organs are hidden, I am unable to say whether any action occurs in them 

 simultaneously with the deposition of eggs. The integument of the body is comjjosed of 

 a very delicate epidermis, beneath which are bundles of longitudinal muscular fibres, 

 connected transversely by others, shorter and more delicate. The length of the largest 

 specimens dug out from tlie rock Avould vary from ^ to f ths of an inch. 



Between the two rows of tentacles, on the nem-al side of the body, but nearer the 

 haemal row, is the mouth, which is somewhat elliptic, ciliated, and surrounded by a miis- 

 cular sphincter, and covered by a delicate transparent marginated crescentic Hp, attached 

 by its concave edge to the convex portion of the lophophore. The mouth opens into a 

 delicate expansible (non-ciliated ?) oesojihagus, which occupies the middle of the body. I 

 have failed to detect the bands of areolar tissue aUuded to by Dr. Wright as the stays of 

 the alimentary canal. Just below the portion of the body protruded from the tube, the 

 oesophagus opens, apparently through a sphincter, into an oblong stomach, richly 

 ciliated, in which the food revolves rapidly in pellets, as in Pedicellina. What lies beneath 

 the stomach I am vmable to state decisively. The lower part of the body is so deeply 

 imbedded in the hard rock, and its substance so fragile, while the tube is comparatively 

 so tough, that very many hours of effort failed to extract one in perfect integrity ; and 

 the lower portion is so opaque that its walls do not permit its contents to be seen. I 

 believe, however, that the stomach terminates in a very capacious intestine, which, filled 

 with faeces, occupies the lower portion of the body, and which, traversing the whole tube 

 and gradually narrowing, ascends again to terminate in a circular anus lying a little 

 above, behind, and between the ridges made by the oviducts between the extremities of 

 the rami of the lophophore The intestine lies above the oesophagus and the great 

 blood-vessel, but beneath the oviduct. It is exceedingly delicate in structure, and can 

 scarcely be luade out except by its contents. It is not ciliated. The fajces are voided by 

 jerks, in fusiform pellets connected by slender filaments, and frequently equal in length 

 the whole exposed portion of the body. 



The only organs to which hepatic functions could be attributed were some coloured 

 cells on the walls of the stomach. 



I could detect no nervous system : but this part of the organization demands further 

 investigation ; and it is possible that the two obscure organs mentioned as being present 

 at the posterior part of the floor of the lophophore may be oesophageal ganglia. There are 

 no eye-spots ; nor does the animal show any sensibility to the influence of Ught. 



Above the oesojjhagus, and attached to it by one margin, lies the great blood-vessel, 



