386 REPORT— 1900. 



ASCIDI^ SIMPLICES. 



Fam. 1. — CLAVELiNiDiE. I Ciona intestinalis, L. 



Phallusia mammillata, Cuv. 



Clavelina lepadiformis, O.F.M. 

 Diazona violacea, Sav. 

 Rhopalcea neapolitana, Phil. 



Fam. 2. — Ascidiid.e. 

 Ascidia mentula, L. 



Fam. 3. — CyNXHiiDiE. 



Cynthia dura, Heller 

 Microcosjrms vulgaris, Heller 

 Styda canopoides, Heller 

 Polycarpa gloinerata, Alder 

 Forbesella tessellata, Forbes 



Report on the Occupation of a Table at the Zoological Station at Naples 

 during March and April 1900. 



d. The Anatomy of Phyllirkoe, the Coilenterate Plcmkton, and certain 

 Calenterata. By R. T. Gunthee, M.A., Magdalen College, Oxford. 



The Committee of the British Association permitted me to use the 

 Table hired by the British Association during the summer months of the 

 present year, for the prosecution of certain researches on pelagic organisms 

 in which I have been for some time and am at present engaged. Since 

 it was inconvenient for me to work at Naples during the months of May 

 and June, I was, by the generous courtesy of the Director of the Zoological 

 Station, permitted to commence the occupation of the Table during my 

 Easter vacation at a time when the resources of the station are very 

 severely taxed by the great concourse of zoologists who annually assemble 

 there at that season. For this especial act of kindness, in addition to 

 so many others I have been shown by Dr. Dohrn, I desire to ofier my 

 hearty thanks. 



The Table of the British Association was occupied by me for about a 

 month — between March 24 and April 2-5, 1900. 



My attention was principally devoted to a detailed study of the 

 anatomy of Phyllirkoe and to a daily examination of the Ccelenterate 

 portion of the plankton of the bay. The general character of the latter 

 was very similar to what it was on a former occasion when I had the 

 good fortune to examine it, but owing to the prevalence of westerly winds 

 during parts of March and April, an unusual quantity of Velella and 

 Physalia appeared in the bay. All along the sandy foreshore of Cuma, 

 which is open to the west, sea and beach were remarkably delimited by 

 Velella; extending as a blue band about a foot or so broad and many miles 

 in length. In consequence, too, of the same prevailing winds Physalia, 

 which is extremely rare at Naples, and which has not been taken for 

 twelve years, as I am informed by my friend Cav. Lo Bianco, appeared in 

 great numbers, and was probably drifted in from the Atlantic as a con- 

 sequence of the exceptional meteorological conditions. 



I availed myself of the opportunity of verifying the statement that the 

 characteristic blue colouring-matter of Velella (zoocyanin) may be very 

 conveniently extracted from the tissues by maceration in a saturated 

 solution of potassium acetate. A solution prepared on March 26, which 

 has been kept in the dark, still retains its blue colour, and will be sub- 

 mitted to spectroscopic examination on my return to England. As the 

 result of the action of the potassium acetate, the ' yellow cells ' or sym- 

 biotic algse, which are yellow in the tissues of the Velella, turn green. In 

 several of the species examined the arrangement of these yellow cells was 

 in groups of 2, 4, 8, or other multiples of 2. 



