254 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



and C. japonica, in the condition of the' mantle, and the 

 form of the alimentary canal, dorsal tubercle, &c. That 

 leaves the common British species Gorella parallelogramma 

 and the Arctic form G. borealis, described by Traustedt 

 from the Kara Sea, and these are certainly the nearest 

 relations of our North Pacific species. From C. paral- 

 lelogramma, however, our form can be distinguished by 

 the almost complete absence of muscles in the mantle, 

 and by the greater irregularity of the branchial sac (fig. 3) 

 and the form of the dorsal tubercle (fig. 4) ; while from 

 C. borealis (which it is most like) it differs in the external 

 shape, the proportions of the alimentary canal (fig. 2) and 

 the greater irregularity of the branchial sac. It is impos- 

 sible in considering the characters of this series of Gorella, 

 to avoid the conclusion that these last three, G. paral- 

 lelogramma, C. borealis, and C. ivillmeriana, are represen- 

 tative species, and that the Kara Sea form is intermediate 

 in some respects between the British and the Northern 

 Pacific species. 



The branchial sac of our specimen contained several 

 specimens of the parasitic Copepod Doropygus pulex, 

 Thorell, which have been kindly identified for me by 

 Mr. I. C. Thompson. 



Fig. 1, on PI. XL, shows the single specimen of G. 

 ivillmeriana from the left side, natural size. Pig. 2 

 shows the alimentary and reproductive viscera from the 

 right side, slightly enlarged. Pig. 3 shows a part of the 

 branchial sac from the inside ; and fig. 4 shows the dorsal 

 tubercle, and some of the tentacles and dorsal languets. 

 At the anterior end of the branchial sac the internal 

 longitudinal bars become irregular and incomplete, and 

 are then found as simple or bifurcating buds growing out 

 from the transverse vessels of the branchial sac. 



