146 THE VOYAGE OF H.M.S. CHALLENGER. 
10. In some genera the inner surface of the integument is covered by a net-work of 
nerves and ganglia in connection with, and most probably issuing from, the integu- 
mentary nerves given off by the supracesophageal ganglion, 
11. In the most primitive condition the eye of the Pyenogonid consists of a rounded 
transparent part of the integument, the inner surface of which is furnished with some 
small ganglia and nerve-fibres issuing from the integumentary nerve bundle. The highly 
developed eye of the shallow-water species shows ganglionic cells, distinct retinal rods, 
and a lens consisting of a thickened part of the chitinous skin of the animal. 
12. Those eyes which have lost their pigment and their retinal rods are rudimentary. 
They cannot be considered as forming the transition between the highly-developed eye 
and its most primitive condition. 
13. That part of the cesophagus which runs through the proboscis has the function of 
a masticating apparatus. Where the cesophagus enters the intestinal tract (the stomach) 
small glands (pancreatic, most probably) are present. 
14. The original condition of the genital glands is in the form of a U-shaped mass, 
placed above the intestine and giving off branches which penetrate the legs. Whereas for 
the male glands the original form prevails in most (all ?) genera, for the female glands it 
seems to be a rule that only the lateral parts entering the legs are developed. The genital 
pores of the females are larger than those of the males ; they are found ventrally towards 
the extremity of the second joint of the leg. Whereas for the females it is the rule that 
these pores are present on all the legs; it often happens in the males that they are only 
present on the two or three hindmost pair of legs. 
15. There are always distinct vasa efferentia, but there are not always true oviducts. 
16. In Nymphon brevicaudatum, Miers, females also bear the eggs on the ovigerous legs. 
17. The larva creeping out of the egg is already furnished with an azygous outgrowth 
of the region surrounding the mouth (the proboscis). Asa rule in that stage only three 
pairs of appendages (the later cephalic ones) are present. 
18. These larvee are often furnished on their mandibles with an apparatus producing a 
single or numerous threads, wherewith the young is attached to the ovigerous leg of its 
parent. 
19. About the relation in which the Pycnogonida stand to either the Crustacea or 
the Arachnida we know as much or as little as we do about the relation in which these 
two classes Arthropoda stand to each other. 
Note.—While I was engaged in preparing the index of this report, and after the 
rest of it had been printed off, Mr Edmund B. Wilson of Baltimore kindly sent me two 
papers which he had recently published. In one (the Pycnogonida of New England and 
Adjacent Waters, Report of the United States Commissioner of Fish and Fisheries, part 
vi. for 1878, pp. 463-506, pls. i—vii.) the author gives an account of the present know- 
