EXPLANATION OF PLATES. 



Plate 1. 



Eig. 1. General view of the viscera of Doris pilosa, the dorsal kin being laid open : — a, buccal mass ; 

 b, portion of stomach ; c, intestine ; d, pancreatic organ ; e, e, liver ; /, mucus-gland in 

 connexion with the female channel; g, portion of testis; h, spermatheca; i, accessory 

 spermatheca ; j, pericardium ; k, ventricle ; I, auricle ; m, m, lateral trunk- veins passing 

 into the auricle from the skin ; n, trunk-vein from the branchiae leading into the 

 auricle ; o, portal heart ; p, p, upper wall of renal organ exhibiting network of vessels ; 

 q, folliculated gland-like body apparently connected with the vascular system. 



2. General view of the viscera of D. tuber culata seen from above : — a, buccal mass ; b, stomach, 



exhibiting on its surface a network of nervous filaments, with a few minute ganglia, 

 being a portion of the sympathetic system ; c, intestine ; d, d, liver, with the principal 

 arterial trunks of the liver and renal organ seen on the surface ; e, retracted penis ; 

 /, mucus-gland belonging to the female channel; g, spermatheca; h, vagina leading 

 from the external orifice to the same; i, pericardium ; j, ventricle, with the aorta passing 

 from the apex in front ; k, auricle ; I, I, lateral trunk-veins leading from the skin to the 

 auricle ; m, trunk-vein leading from the branchiae to the auricle ; n, portal heart, 

 opening into pericardium; o, gland-like body in connexion with the vascular system; 

 p, supra-oesophageal ganglions with the nerves passing from them; q, branchial ganglions 

 of the sympathetic system ; r, retractor muscles of the channel of the mouth. 



3. View of, the buccal cavity of D. pilosa, from above : — a, oesophagus; b, membranous crop 



at the commencement of the same; c, oral opening; d, outer lip; e, inner lip; 

 /, channel of the mouth ; g, buccal lip ; h, prehensile collar in connexion with the 

 same ; i, rudimentary jaws ; j, walls of the anterior portion of buccal cavity; k, fleshy 

 support of the tongue ; I, tongue ; m, external sac within which the tubular portion of 

 the tongue is lodged. 



4. Side view of the tongue of D. pilosa, the fleshy support being removed : — a, anterior 



prehensile portion; b, posterior tubular portion. 



5. Portion of the tongue, more highly magnified, seen from above. 



6. View of the buccal cavity of D. tuherculata, seen from above : — a, oesophagus ; b, oral 



opening ; c, outer lip ; d, inner lip ; e, channel of the mouth ; /, buccal lip ; g, walls 

 of buccal cavity; h, fleshy support of the tongue ; i, tongue : j } membranous septum 

 dividing the anterior from the posterior portion of the tongue ; k, retractor muscles of 

 the channel of the mouth ; I, I, retractor muscles of buccal mass. 



7. Side view of the tongue of D. tuber culata, without the fleshy support : — a, anterior portion ; 



b, posterior or tubular portion ; c, membranous septum dividing the two portions. 



8. Central portion of two rows of spines from the tongue of D. tuberculata. 



9. A single spine more highly magnified. 



10. Central portion of two rows of spines from the tongue of D. repanda : — a, central spine ; 



b, lateral spines. 



11. A single lateral spine more highly magnified. 



