2:>0 KINGSLEY. [Vol. VIII. 



30. The invaginate character of the median eyes. 



31. The long stomodoeum. 



32. The large mesenteron. 



33. The large midgut glands (hepatopancreas) emptying by 

 metameric ducts. 



34. The short proctodaeum. 



III. Limulus and the Arachnids agree with the Crustacea, 

 and differ from the "Tracheates" in points 14, 21, 27, 31, and 

 also in : 



35. The absence of any differentiated head. 



36. The position of the genital ducts in the appendages 

 near the middle of the body. 



37. The development of the respiratory organs in connec- 

 tion with the appendages. 



38. The paired sexual openings. 



Several of the foregoing points need but little discussion 

 since they have already been considered both by Prof. Lan- 

 kester ('81) and by myself. It is, however, to be noted that 

 this enumeration of resemblances and differences omits all 

 reference to characters which are common to all great groups 

 of Arthropods, and also to those which are peculiar to any 

 one group, except so far as they are, apparently, based upon 

 misconceptions. It must also be mentioned that Peripatus is 

 omitted from the discussion, since, notwithstanding the recent 

 researches of von Kennel, Sedgwick, Sclater and Miss Sheldon, 

 its position in the Arthropod phylum is not beyond question. 

 So too with the chilognathous Myriapods, since for reasons 

 which will appear later, their relations to the chilopods are 

 exceedingly doubtful. 



I have already discussed in the previous part of this paper 

 the evidence presented by the ovigenesis, in which there is a 

 close parallel between the Arachnids and Limulus, the ^^g in 

 both passing into a follicle formed by the separation of the 

 tunica propria from the germinal epithelium. I have also 

 considered the matter of the origin of the entoderm in both 

 Limulus and the Arachnids (and Pycnogonids) by delamination, 

 and the early segmentation of the body, closely parallel in both 

 groups, before the appearance of the legs. A farther point 



