Specimens of Ce-p\\a\o(\iscns densus. 439 



tliose with two testes, and those with an ovary and a testis. 

 The gonads vary in their state of maturity in different zooids. 

 The young ovaries are rather longer and straigliter than 

 those figured as C and D in text-fig. 7 of the ' Terra Nova' 

 Report (i6^ p. 46), and the pigment-granules around the 

 oviducal aperture are bhick rather than red. In the material 

 in the smaller bottle, received from Prof. IM'Iiitosh, all the 

 zooids that were examined had ripe gonads. Free ova occur 

 in this material ; they are found among the buds, in the 

 deeper end of the coenoecial tube, there being not more than 

 one ovum in any one tube. The ova are free, and not 

 attached by a stalk ; they measure 0"9 mm. in length and 

 0*6 mm. in width, and the two ends are similar. In two 

 cases where a free ovum was present in the coenoecial tube 

 among the tangle of buds it was found that the zooid in- 

 Iiabiting the tube was hermaphrodite, and the ovary and 

 testis were both ripe (cf. i6, p. 47, and 17, p. 23). It would 

 be interesting to ascertain if a free ovum ever occurs in a tube 

 inhabited by a male zooid — probably not ; the present material 

 is too limited in bulk to permit of a more extended search in 

 this direction. 



Tlie greatest number of buds found attached to any one 

 zooid is eighteen ; this group includes buds of all stages of 

 development, from the very young stage before the appear- 

 ance of the red line of the shield up to a large bud with small 

 tentacles appearing on the arms (ef. 16, p. 47, text-fig. 8, C 

 and k). Tlie youngest buds, however, are not buds of the 

 main zooid, but arise from the side of the extremity of the 

 stalk of a large bud-^that is to say, the larger buds begin 

 producing the next generation of buds before separating from 

 the parent zooid. The largest bud of the group of eighteen 

 just mentioned had two small buds of its own. 



References. 



(i) Anderssox, K. a. "Eine AViederentdeckuug von Cephalodiscus." 

 Zool. Anz. xxvi. 1903, pp. .:j68-369. 



(2) . "Die Pterobranchier der Sehwedischen Siidpolar-Expe- 



dition, 1901-1903." ^Viss. Ergebn. Scbwedischeu Sddpolar- 

 Expedition, v. (Stockbolai, 1907) pp. 1-122, 8 plates. 



(3) GiiAViKii, C. "Suv line espece nouvelle de Cephalodiscus {C. an- 



derssoni, nov. sp.) pi-ovenant de la Seconde Expedition Antarctique 

 Eran9aise." Bull. Mus. Hi^t. Nat. Paris, 1912, xviii. 3, pp. 146- 

 150, 2 text-figures. 



(4) . ' Deuxieme Expeditii m Antarctique Franfaise, 1908-1910; 



Sci. nat, Documents scientifiques ; l't*5robranclies.' Paris, 1913, 

 pp. 71-86, .5 text-tigures. 



(5) Harmrr, S.F. "On ne-w Localities iov Cephalodiscus," Zool. Anz. 



xxvi. 1903, pp. 593-594. 



(6) . " Tbe Pterobrauchia of the 'Siboga' Expedition, with au 



