20 PYCNOGONIDA. 



Arachnide artrogastro (Koenenia mirabilis) rappresentante di un nnovo ordiue (Microtelyphonida) 

 (1886), which essay follows the preliminary paper without figures by the same author: Intorno ad 

 un nuovo Aracnide artrogastro (Koenenia mirabilis) che crediamo rappresentante d'un nuovo ordine 

 (Microteliphoiiida) (1885). As, however, the treatment by Hansen and Sorensen seems to me to 

 be far more solid than that of Grassi, and as the figures, in which I take most interest, are very 

 fine and distinct, I shall chiefly abide by this treatise written in English, with its plate, to the figure 

 2 of which I shall especially refer, as it shows the animal viewed from the lower side. The homology 

 of the proboscis of Koenenia (<?), which by the authors have been named with the unfortunate ex- 

 pression mouth, while Grassi uses the much better one papilla boccale , with the proboscis 

 of the Protonymphon is conspicuous, and the relation and situation as to the three foremost 

 pairs of limbs is exactly the same. Throvigh the proboscis of Koenenia a transition is next formed 

 to the mouth-structure in the other Arachnida, where I, contrary to Hansen and So r en sen, and to 

 the prevalent opinion, find the same proboscis, and it has only to be pointed out that the proboscis 

 in the other orders of Arachnida, on account of its position between the powerful gnathites, necessarily 

 must become shorter and more strongly chitinous than in Koencnia; and nowhere, perhaps, is the 

 shortening and chitinization so accomplished as in , the Telyphona 1 ) so nearly related to Koenenia. 

 But if the proboscis of Koenenia and thus of the other Arachnida is homologous with that of the 

 Pycnogonida, and if it has never been supposed or is impossible to consider the proboscis of Koenenia 

 as formed by a coalescing of oral parts or gnathites, then it must be said that there is no reason at 

 all to suppose such a coalescing in the proboscis of the Pycnogonida. 



In the figures 7 and 8 is next given a drawing of the proboscis of Koenenia, viewed from the 

 side and from below, but without any contribution as to its inner structure; it is only said that the 

 muscles are very strong, and some fine, indistinct lines in fig. 7 may be taken as an indication of 

 these muscles. It cannot, however, be doubted that it is a sucking apparatus or a pump, as is also 

 shown even by a less strict examination. 



The genera Pallene and Psetidopallcnc show in their larval form, as well in the first as in the 

 second stage, so great a difference when compared with the other larvae of Pycnogonida, that there 

 might seem to be reason enough to set them up as a particular type; but as the difference chiefly 

 consists of a reduction of the embryonal legs or even a disappearing of these, it is morphologically 

 of small importance. I have not seen so young a stage as that I have drawn of Pycnogonum littorale 

 pi. I, fig. i and 2 ; the youngest stage I have seen, is that of Pseudop. spinipes , pi. I , fig. 7 , where the 

 embryo is viewed from the side, lying in the egg, and with distinctly defined cheliforus, proboscis, 

 and foremost pair of ambulatory legs. In the cheliforus, the two outermost joints, the chela, are not 

 yet separated, and every trace of embryonal legs is wanting. That the swelling behind the chelifonis 

 must be the foremost pair of ambulatory legs, and cannot be one of the two pairs of embryonal legs, 



') Thus I cannot agree to the comparison between the proboscis (mouth) of Koenenia and the composite month, 

 with the general addition of the gnathites, of the other Arthropoda, and I think that the difference as to the mouth-struc- 

 ture may best be expressed in this manner that, while in the Arthropoda generally more pairs of limbs , the gnathites , close 

 together around the oral orifice, and are developed with reference to their partaking in the catching of and preliminary 

 dealing with the food, in Koenenia, as well as in the Pycnogonida, all the corresponding limbs are kept away from the oral 

 orifice, which accordingly in these forms is placed freely in the point of the papilla boccale. 



