PSEUDOSCORPIONES. 



27 



Limulus (Ray-Lankester, Bruce). Our knowledge of the ontogeny 

 of the Pedipalpi is unfortunately very incomplete, and this may also 

 be said of Koenenia mirabilis, a form discovered by Grassi (under 

 stones in the plains of Catania), which shows great resemblance to 

 the Pedipalpi, but has been placed by him in a separate order, the 

 Microtelyphonidae, the Palpigradi of Thorell.* This form is said 

 to have no special respiratory organs, and Grassi therefore sees in 

 it a transitionary form between the Gigantostraca and the Arachnida, 

 which has " already lost the gills, but has not yet developed respira- 

 tory organs suited to a terrestial existence " ! We can hardly imagine 



A 



Fig. 15.— Embryos of Chelifer in their envelopes (after Metschnikoff, from Balfour's Text- 

 book). A, early cleavage stage. B, stage in which the blastoderm (6?) has separated from 

 the yolk-masses within. C, splitting of the blastoderm into two layers. The yolk-masses 

 are seen within the egg. A cell-like albuminous tissue appears between the blastoderm 



such a transition, and would rather regard the absence of respiratory 

 organs, if it actually occurs, as a degeneration, such as is met with 

 in other air-inhabiting Arthropoda in cases where the body is dis- 

 tinguished from related forms by its specially small size (e.g., in a 

 few Mites, among the Arachnida, and in Pauropus among the 



Myriopoda). 



III. Pseudoscorpiones. 



The little that is as yet known of the ontogeny of the Pseudoscorpiones does 

 not seem sufficiently well established to enable us to form a decisive judgment 

 with regard to the extraordinary development of these forms. Metschnikoff's 



* [Hansen and Soiiensen (App. Lit. on Palpigradi, No. I.) give a very careful 

 account of Koenenia, and correct many errors in Grassi's description. — Ed.] 



