GONIODORIS. 



(5), which are sessile on the outer margin above, of the cerebroid portion of the upper ganglia. 

 The auditory capsules contain numerous otolithes, and are seated upon the under surface of 

 the upper ganglia, near to their junction with the pedial. 



The buccal ganglia (e, e) occupy their usual position on the buccal mass, immediately 

 behind the oesophagus : they are elliptical, are united across the median line by a longer 

 commissure than usual, and are joined to the upper ganglia by two fine cords {h, h). 

 These ganglia give nerves to the tongue (15), and buccal organ (13, 14), and have attached to 

 them by longish pedicles a pair of gastro-oesophageal ganglia, (/,/), which send two nerves 

 (16) down the oesophagus, and also supply the salivary glands. 



The only traces that we have detected of a sympathetic system are the oesophageal nerves, 

 and the small ganglia, and some minute nerves on the root of the intromittent organ. 



The skin is soft and more or less tuberculated ; and though well supplied with spicula, 

 they are not sufficiently numerous to stiffen the surface. 



EXPLANATION OF THE PLATE. 



Fig. 1. General view of the viscera of Goniodoris nodosa, partially spread out and seen from above: — 

 a, buccal mass ; b, buccal gizzard ; c, c, salivary glands ; d, oesophagus ; e, upper portion of 

 stomach ; /, liver mass ; g, g, intestine ; h, retracted penis ; i, tubular portion of testis ; i, 

 glandular portion of the same ; i" , small tubular or duct-like portion of the same;;', portion of 

 oviduct as it leaves the ovary ; /, dilated portion of the same ; k, k, ovary overlying the liver ; I, 

 mucus-gland of female organs ; m, vaginal tube, leading from the exterior to the spermatheca ; 

 n, spermatheca ; o, tube leading from the same to the oviduct ; p, accessory spermatheca ; g, 

 pericardium ; r, ventricle, seen through the transparent walls of the pericardium ; s, auricle ; 

 t, t, lateral trunk-veins from mantle to auricle ; u, branchio- cardiac vein ; w, portal heart, 

 seen through the transparent membranes of the heart ; w, branchial plumes ; y, renal organ ; 

 z, cerebral ganglions. 



2. Front view of the prehensile collar of Goniodoris nodosa : — a, collar ; b, membranous fringe 

 attached to the inner margin of the same ; c, buccal lip ; d, buccal orifice. 



3. A few of the spines from the prehensile collar of Goniodoris nodosa. 



4. Cerebral ganglions of Goniodoris nodosa : — a, a, cerebroid and branchial ganglions fused into 

 two masses; b, b, pedial ; c, c, olfactory; d, visceral; e, e, buccal; /,/, gastro-oesophageal; g, 

 great oesophageal collar ; h, h, nervous cords connecting the buccal ganglions to the cerebroids ; 

 i, small collar uniting the branchial and visceral ganglions ; 1, olfactory nerves ; 2, nerves 

 supplying the upper portion of the channel of the mouth ; 3, those to the side of the oral 

 channel and oral tentacles ; 4, those to the under side of the channel of the mouth ; 5, eyes, 

 each seated on a small ganglion ; 6, pallial nerves ; 7, a nerve which goes to a small ganglion 

 (j ) seated on the root of the male intromittent organ ; 8, 9, 10, pedial nerves ; 11, 12, visceral 

 nerves ; 13, 14, buccal nerves ; 15, lingual nerves ; 16, oesophageal nerves. 



5. Front view of the rudimentary prehensile collar of Idalia pulchella : — a, spinous lobes; b, 

 buccal lip ; c, oral opening. 



6. Two spines from the same highly magnified. 



7. Front view of prehensile collar of Ancula cristata : — a, upper margin. 



8. A few of the spines from the same much enlarged. 



