140 MESSRS. ALDER AND HANCOCK ON 



The liver is, in a great measure, retained within the visceral cavity, as an elongated, 

 folliculated mass, the anterior extremity of which, extending up the left side of the sto- 

 mach, is attached to that viscus, and opens into it a little behind the oesophagus. Fol- 

 liculated branches pass from this biliary organ to the branchial tufts, and penetrate to 

 the papillae, within which they terminate in slightly branched or folliculated prolonga- 

 tions. The anterior pair of tufts, however, receive their branches from folliculated 

 masses attached to the dorsal wall of the stomach in front, which masses open into the 

 anterior portion of the stomach. 



The reproductive organs, as far as they could be determined, resemble those of Den- 

 dronotus ; and, as in it, the ovary lies above the liver or central folliculated trunk of 

 the gastro-hepatic system. 



The vascular system is also similar to that of Dendronotus. The heart occupies a 

 distinct pericardium, on opening which it is easy to see that the blood is returned from 

 the branchiae by four lateral vessels, two in front and two behind. The gills are very 

 peculiar : they are in the form of pedunculated tufts, each tuft being composed of simple 

 papillae and laminated plumes ; and it is evident that the blood takes a definite course 

 through both structures. It finds its way through the cellular tissue of the peduncle 

 into all the divisions of the tufts ; it then passes over the aerating surfaces, and reaches 

 the efferent branchial channels which run down the outer margins of the papillae and 

 plumes, and unite at the base to form one common trunk, which descends at the posterior 

 margin of the peduncle. Arrived at this point, the blood falls into the great lateral 

 channels that lead to the auricle. From these facts there can be little doubt that the 

 papillae, as well as the plumes, are gills, only the latter are a little more differentiated 

 or somewhat more highly organized. That the one is only the other modified, we have 

 a proof in an abnormally developed plume which one of the specimens exhibited : this 

 plume retained to a considerable extent the appearance of a papilla. 



The cerebral ganglions are arranged as in Dendronotus. The cerebroid and branchial 

 are fused into two oblong masses, which are united across the median line ; and the pedal 

 lie beneath the oesophagus : the commissural cord has disappeared, these latter ganglions 

 being united by their inner margins below the oesophagus. 



BORNELLA DIGITATA, AdttmS. (PI. XXXIII. figS. 8, 9.) 



Body nearly linear, rounded above, flesh-coloured, covered with crimson reticulated 

 lines. Sides of the head produced in front into two star-like, rounded lobes, with six or 

 seven radiating filaments on the margin and others beneath. Tentacles clavate or fusi- 

 form, obliquely laminated, retractile within long cylindrical sheaths, the upper margin 

 of which bears four linear papillae, one of which is much larger than the rest and clavate, 

 banded near the top with crimson, and tipped with yellow. Branchial processes six on 

 each side of the back, in smgle series, diminishing posteriorly : they are pedunculated, 

 branching above into two or three stout papillae, each with a band of crimson, above 



