NUDIBRANCHIATA OF THE L.M.B.C. DISTRICT. 137 



only a narrow basal tract free from them, (PL VI. fig. 9), 

 in Anciila they are confined to the terminal one-third or so 

 of the cerata. Possibly these glands, both in Polycera and 

 Aacida, correspond to those found in a similar position 

 in Aplf/sia (PI. VII. fig. 1), viz., along the edges of the 

 epipodia. In Aplysia punctata, however, these epipodial 

 glands are smaller and not so conspicuous, those of the 

 under surface of the mantle edge being relatively larger 

 and more numerous (PL VII. fig. 2). 



B. CEKATONOTA (^ CLADOHEPATICA.) 

 Family DoTONiDiE. 



Doto co7'onata, Gmelin. 



Dredged in Turbot Hole, off Puftin Island, August, 1889. 



With the view of determining the structure of the 

 cerata, and especially the meaning of the little pigmented 

 projections which give them their turretted appearance 

 (PL IX. fig. 1), we have made a number of serial sections 

 both longitudinal and transverse. The hepatic caeca in 

 the cerata are very large and are branched and swollen, so 

 that usually several large hepatic cavities are found cut in 

 each section (PL IX. fig. 1).* Between the hepatic caeca 

 and the ectoderm we find almost a continuous layer of 

 gland cells which stain deeply with picrocarmine and are 

 arranged in elongated clumps lying parallel with the 

 ectoderm and usually two or three cells thick (PL IX. 

 fig. 3, (/L). On the pigmented projections the columnar 

 ectoderm is found to become rapidly cubical and then 

 almost squamous (PL IX. figs. 2 and 4, k), while the dome- 

 shaped cavity below the thin ectoderm is nearly filled up 



* For the general relations of the hepatic cpeca in the cerata to the parts 

 of the liver in the body see Herdnian, Quart. Jour. Microsc. Sci., vol. xxxi., 

 p. 51, and pi. ix. 



