106 Mr. Forbes on new British Mollusca. 



specific characters in this genus appear to be : 1st, the gene- 

 ral form as regards elongation ; 2nd, the smoothness or rough- 

 ness of the back, including the number of papillae, when pre- 

 sent; and 3rd, the form of the oral or sustentacula. The 

 genus ranges from the northern shores of Britain to the south 

 of Italy. 



IV. MoNTAGUA viRiBis. Nov, Sp, Forbes, Plate II. 

 fig. 18. 



M, elongata alba, branchiis elongatis viridibus apicibus albis, 



in seriebus quinque digestis : tentaculis superioribus longi- 



oribus, Lon. 0^ unc. 



The body of this very distinct new species is lanceolate, 

 tapering gradually to the finely attenuate tail. On the back 

 there are five transverse rows of long branchiae, seven or eight 

 in the broadest> rows, which are those placed foremost. There 

 appear to be no papillae on the sides as in the two other 

 British Montaguce, The head is furnished with four long 

 tentacula, the uppermost ones longest, and have two large 

 black eyes at their bases. These tentacula do not appear to 

 be ciliated : they are rugose, or wrinkled concentrically. In 

 this respect they differ from the tentacula of such Eolidce as 

 have their branchiae arranged in lateral tufts, which have the 

 upper tentacula ringed and covered with vibratile cilia. Such 

 cilia are seen also on the laminated tentacula of Doris: those 

 on the upper tentacula of Goniodoris nodosa are larger than 

 the branchial cilia in that species: the lower or oral tentacula 

 are not so covered. The upper and lower tentacula among 

 most of the Nudibranchia, perhaps in all, are evidently very 

 different organs, the latter for touch, the former for some 

 finer sense. 



The body and tentacula of Montagua viridis are white, 

 saving a narrow greenish line down the back. The branchiae 

 are green with white ocellated tips and sometimes a few scat- 

 tered dark green spots. The green colour is caused by a cir- 

 culating fluid, the particles of which may be seen rushing 

 from the central vessel or dorsal stripe into the branchiae, 

 where they remain for a short time, and then flow back. 



This pretty little species was found on a specimen of An- 



