Royal Physical Society. 167 



others in their immediate vicinity. Hence I think we must suppose some 

 auxiliary propelling apparatus to be interposed between the artery and 

 the tentacular capillaries. The opacity of the cup, from which the ten- 

 tacles spring, not only prevented me from detecting any such arrange- 

 ment, but also from observing the mode of communication between the 

 capillaries and the venous system. The muscular system consisted of a 

 layer of flat longitudinal bands immediately beneath the integument, and 

 interior to these fine circular fibres could be traced with extreme difficulty 

 under a power of 300 diameters. The viscera were retained in their 

 place by delicate areolar fibres. 



The second animal I have to describe, and which is probably another 

 species of the last, was found in a decayed oyster shell dredged from the 

 Firth of Forth near Inchkeith. The shell was inhabited by Clione celata, 

 and while examining the projecting processes of the sponge, I noticed a 

 great number of animals which I for some time mistook for Lepralia, 

 until my attention was arrested by a slight want of symmetry in the 

 circle of the tentacles. It was not a circle, but rather an oval very 

 slightly flattened on one side. A power of 200 diameters was brought 

 to bear on one of the animals, and it appeared as shown in fig. 2. The 

 body, slightly projecting from a membranous tube buried in the shell, 

 carried a crown of eighteen tentacles finely ciliated, but not presenting 

 the appearance of moving teeth. They were not connected by membrane 

 at their base. Within the tentacles, a constant stream of blood-globules 

 ascended and descended precisely as in the animal before described in this 

 communication, but the opacity of the cup prevented the detection of any 

 larger vessels. I succeeded in digging only one of these animals with its 

 tube entire from the shell. It was about half an inch in length. The 

 long gullet terminated in a globular gizzard, the interior of which was 

 paved with bodies apparently cartilaginous, and of prismatic shape. The 

 gizzard communicated below with a thick walled stomach. No ascending 

 rectum was detected ; but I inferred it to exist, hidden behind the sto- 

 mach, as a thin membranous tube containing fusiform faeces was observed 

 passing upwards to the tentacular crown. The blood-vessels were dis- 

 placed, and lying twisted together within the body. 



These animals have been examined by the most eminent naturalists in 

 this city, who consider that they possess great interest. They appear to 

 me to possess characters common to the Polyzoa {Plumatella, Pedicel- 

 Una), the Tunicata (in which the circulation of red blood has been no- 

 ticed by Milne-Edwards), and the Annelida, in which last class they pro- 

 bably ought to take their place. I propose to designate the first of these 

 animals Phoronis* hippocrepia, the second Phoronis ovalis. 



* Phoronis, one of the surnames of Isis. 



