NUDIBEANCHIATA OF THE L.M.B.C. DISTRICT. 143 



scattered over the tips of the dorsal and oral tentacles. 

 The eyes are very distinct, and are placed some way behind 

 the bases of the dorsal tentacles. Sections however show 

 that they are sessile upon the cerebral ganglia. 



The cnidophorous sac is pyriform in outline, the upper 

 end being pointed while the lower wider end communicates 

 with the apex of the hepatic caecum by a short straight 

 tube (PI. YIII. fig. 7). The wall of the cnidophorous sac 

 is unusually muscular, and while one of the animals w^as 

 under observation in the living condition w^e saw a large 

 number of the cnida expelled with force from the terminal 

 opening (PL YIII. fig. 8.) in the exploded or evaginated 

 condition. The cnida are large (measuring 0'028 mm. in 

 length and 0*01 mm. in breadth) and are of an ellipsoidal 

 shape (PI. VIII. fig. 9).* The thread is distinctly seen to 

 be coiled along the axis of the cell and not transversely 

 to it as in Facel'nia drummoinU and other species. When 

 evaginated the thread is seen to be provided with num- 

 erous long sharp spines placed alternately so as to give 

 rise to a zig-zag appearance (PI. VIII. fig. 9). 



Galvina pk'ta, Aid. and Hanc. 



We collected half a dozen specimens of this species at 

 Hilbre on September 9th, 1889, and several on March 21st, 

 1890; and Mr. A. 0. Walker dredged a specimen in 

 Colwyn Bay in February, 1890. It appears to be becom- 

 ing more common in the district. 



Figure 11 on Plate IX. shows a transverse section 

 through the tip of one of the cerata of this species. On 

 the inner side of the large ectoderm cells is found a thin 

 layer of connective tissue ime.s.), then an irregular series 

 of blood sinuses, then another thin layer of connective 

 tissue, and then, occupying the centre of the section, is 



* Described by Vayssiere as reniform (loc. eit., p. 78.) 



