( 377 3 



XXX. Oil the Anatomical Charaeters of an Australian species o/" Perophora. By John 

 Denis Macdonald, F.E.S., Assistant-SurgeoH of H.M.S. 'Herald,' commanded by 

 Captain's.. M. DENHAM,i2.iV., F.B.S. Comnumicated by George 'RvsK,E8q., F.B.S., 

 F.L.S. 



Read February 17th, 1859. 



JjURING om- stay at King George's Sound, the dredge obtained several specimens 

 of a very interesting compound Tunicary, belonging to the " social " division so called, 

 and which I believe to be a new species of the genus Perophora. The points in which it 

 differs from the known species appear to me to be too trifling to warrant the fabrication 

 of a new genus for its reception. I shall therefore name it Perophora Sutchisoni, after its 

 lirst discoverer, Lieut. John Hutchison, R.N. 



The zooids are about one-fifth of an inch in length, pyriform in shape, and supported on 

 alternate tubular foot-stalks of a corneous texture, with one or more transverse articula- 

 tions. These pedicels are continuous at their base with a tubular axis, from which they 

 appear to be derived by simple extension of its waUs without articulation. 



The principal trunk in the specimen before me is firmly fixed upon a sprig of Amphi- 

 bolis antarctica, over which its rather irregularly-divided branches extend themselves, 

 occasionally drooping freely, like the tender sprays of a climbing plant. 



No articulations are anywhere to be found except in the pedicels of the zooids, whose 

 test commences at a definite line, where the corneous tissue of the pedicels terminates. 



The test is finely coated over with a miaute siliceous grit iaterspersed with Eorami- 

 nifera and calcareous atoms. 



When all these adhering particles are removed by cautious immersion in dilute nitric 

 acid, which destroys all the carbonate of lime and loosens the attachment of the siliceous 

 elements, their impressions are left on the surface of the test, and here and there on that 

 of the axis, which thence presents a deeply pitted appearance. 



The internal surface of the tubular axis is lined throughout mth a very distinct epi- 

 thelial membrane, obviously connected mth its nutrition ; and in the Little buds, wliicli 

 spring, botanically speaking, in the indefinite mode, from the growing branches, the 

 cuecal dilatation of the rudimentary test is lined with an extension of the same membrane. 

 This lining, however, is not to be confomided with the true pallio-vascular system which 

 is contained vidthin it, and consists of a simple branched tube exactly corresponding ^^-ith 

 the trunks and ramifications of the corneous axis, while the coats of the tubules which 

 enter the pedicels of the zooids are continuous with the mantle. Thence results a sort of 

 " ccenosarc," exliibiting a remarkalile analogy to that of the Sertularians, an analogy which 

 is still further sustained by the nature of the sclerous axis just described. This, however, 

 may be regarded as perfectly homologous with the repent tubes and free pedicels of 

 Laguncitla, Pedicellina, and other Polyzoa. 



The branchial and cloacal openings present little or no external prominence, and arc 



VOL. XXII. 3 D 



