1906.] ox THE ASCIDIAXS OF CAPE ^"EEDE ISLAXD. 903 



bases near the skin. A similar comljination of prociyptic colo]?a- 

 tion when at rest and of aposematic coloration when distui'bed, 

 is shown by the large Indian Mygaloid Spider Pcedlotheria and 

 by many of the Lycosidfe *. 



The aboye-mentioned facts and theoiies are based upon obser- 

 yations of the Porcupines that haye liyed during the past three 

 years in the Society's Grardens. 



Dr. C. G. Sehgmann. F.Z.S., exhibited two skulls of male 

 Domestic Sheep, and made the following remarks : — The two 

 heads shown contrast the form of skull of the normal ram of the 

 Herdwick breed (in which only the males haye horns) and a ram 

 of the same age and breed castrated in infancy. The skull of the 

 castrated sheep or wether is less rugged ancl the bones thinner, 

 but besides such general differences and the obyious absence of 

 horns the plane of the os frontis is continued backwards behind 

 the orbits at a yery obtuse angle. In the skull of the normal ram 

 the plane of the frontal behind the orbit lies almost at right 

 angles with the interorbital portion of the bone, the horn-cores 

 arising from the upper or horizontal area. Although the skull 

 generally is thicker in the normal ram than in the wether, this 

 alone does not account for the difference in external form, seeing 

 that the cr-anial cayity presents a corresponding extension in the 

 frontal region. It is worth noting that the conformation of the 

 skull of the castrated animal resembles that of the hornless ewe 

 of the breed. 



The following papers were read ; — 



1. On Collections of the Cape Yerde Island Marine Fauna, 

 made by Cyril Crossland. M.A. (Cantab.), B.Sc. (Lend.), 

 F.Z.S., o£ St, Andrews Uniyersity. July to September 

 1904. — The Ascidia>s"s. By Johx RE^^^^E, D.Sc, and 

 Ha KEY TTiSEMAX. M.A., B.Sc. Uniyersity of Aberdeen. f 



[Received October 12, 1906.J 



(Plates LXIT. t LXV.i) 



This memoir deals with the Ascidians collected by Mr. Cross- 

 land at Cape Verde in the year 1904. Although a fairly abundant 

 supply of material was secured, it has not proyed particularly 

 rich in species. In all, examples of only ten forms were collected, 

 two of which appear to be new to science. Xotes regarding 

 localities are meagre ; most of the specimens appear to haye been 

 obtained at ]Mattiota. St. Vincent Harbour. ' 



* See Pocock, Ann. Mag. Xat. Hist. (7) iii. p. 84, 1899. 



f The expenses of Mr. Crossland's collecting trip wei'e borne by the Carnegie 

 Trustees. 



X For explanation of the Plates see p. 910. 



Proc. Zool. Soc— 1906. Xo. LX. 60 



