

limbs in the Arachnida is six pairs, l>ut in the Pycnogonida seven pairs. But, as I 

 m in tlie foregoing, the seven pairs of limbs in the latter animals are not all i 

 1 the typical number ol pairs is not seven, but nine. Of these nine pairs of limbs 

 ii last pairs, the ambulator) legs, arc- not at all homologous with the ambulator] 

 • at in all likelihood with the four pairs of small processes that have been pointed out in 

 the Arachnid-embryo, cp. Balfour, Notes on the Development of the Araneina, t88o, and 

 on the I »e\ elopment of . Igelt na ncevia^ t886. I i< >tli the mentioned authors represent l < • 1 1 r 

 distinct beginnings of limbs arising from the abdomen of an embryo of an Agclena^ Balfour, 

 pLXIX, pp. or pp. i pp. 4, of Ag. labyrtnthica, and L»ocy, I.e. pi. II IV, fig. 7 11, 13 1 j, 



app. ol an These beginnings which may reach a rather considerable length, 



lied provisional appendages , a name also adopted by Locy. < »n the other hand. 

 I kn<>\\ of no instance- of the genitals or their excretory ducts in any Arthropod being found in the 

 thorax or the limbs of this part, as would be the result of the common interpretation of the ambu- 

 l the Pycnogonida. 3) Furthermore we find in the Pycnogonida an organ so decidedly 

 he Arachnid-type as the chelifori, with which also join \\ the embryonal byssus-glands 

 lion: of the poison-glands of the Arachnida. The want of particular respiratory 01 ives 



no information with regard to systematism , but it may be said to point to an origin or development 

 a primitive, larve-like forms. 5) Finally the presence of auxiliary claws (i. e. real claws) is an 

 important feature in the Arachnida in contradistinction to the Crustacea. 



Relying on the points given in the foregoing, I think myself justified in classing the Pycnog- 

 onida among the Arachnida, as a group which with regard to the outer appearance is ver) much 

 - it has also become very strange by a strong development of organs that in other Arach- 

 only begun, or have been reduced, and upon the whole adopted to the life in the water, 



'.'. the sea. 



When we next pass to the inner systematism of the Pycnogonida, or the consecutive order 



of the species, we shall first have to consider that the species, as far as they are known, form a close 



and united - : forms, SO that there can he no question of dividing them into different -roups, 



tiding to the division into orders in the animal world in general, or in the Arthropoda in 



ticular. Even if we should follow the common notion, and consider these animals as having their 



le the acknowledged four classes of Arthropoda, they would not for that reason become a 



fifth me rank as the other classes, nor will it he necessary to divide them into a smaller 



. suborders, families, subfamilies, genera, subgenera, species, and subspecies. 



ourse easily be put up, and have partly been put up; but then when 



Mich frames, these frames soon appear to be quite artificial, 



S may be pi well at one place as at the other. Therefore we also see, how the 



different authors, referred, now to one genus or family, now to another, or even 



The genera and families, of course, are still less decidedly fixed, but 



and to an extent, unknown or inconceivable inside the class of In- 



1 development, as it has been shown in the section on 

 ment, tin I families that have been put up. have in reality only been 



