COPPINIA ARCTA. 219 



quantity of granular matter, which pushes it still further 

 from the rest of the community." 



The ova are produced in the cavities or compartments 

 which pervade the common connecting-substance, and 

 give a tessellated appearance to its upper surface ; they 

 are found in great numbers clustering around the tubes of 

 the hydrothecse, in the upper portion of the matrix, a 

 little below the surface. I have never seen them in the 

 deeper parts of it. After the escape of the planules, a 

 small aperture is visible in the covering of each compart- 

 ment. Dalyell, from whom we have the fullest account 

 of this zoophyte, throws no light on the nature of the 

 ovarian chamber or the development of the ovum; and 

 in the few cases in which I have had the opportunity of 

 examining recent specimens, I was unable to determine 

 these points. 



The ova lie singly or in clusters, and without any regu- 

 larity of arrangement, within the matrix. Each of them 

 is enclosed in a delicate, transparent membrane. 



The planule is elongate, broad at one end, and tapering 

 off towards the other, about one-third of a line in length, 

 and not ciliated. It moves in worm-fashion, and is of a 

 greenish-yellow colour. When it ceases to move, accord- 

 ing to Dalyell, the body becomes round and deeply annu- 

 lated, exhibiting a number of prominent segments. One 

 end enlarges while the other is elongating, and the latter 

 is moulded into a calycle with its contained polypite. 



C. ARCTA, Dalyell. 



SERTULARIA ARCTA, Dalyell, Bare and Eeraark. An. Scotl. i. 224, pi. xlii. 

 COPPINIA MIRABILIS, Hitssfill, Zoologist, No. 09, 2223; Trans. Microscop. Soc. 

 iii. 160, pi. xxi. figs. 1, 2. 



Plate XLI. fig. 5. 



ZOOPHYTE forming small, irregular, encrusting masses of 



