32 



Gael Bovallius, The Oxycephalids. 



This is the same form of prehensile organ 

 which exists in the third and fourth and also in 

 the fifth pair of perseopoda in Enthemisto and Para- 

 themisto. Moreover the folding hand is common 

 in the Amphipoda Gammaridea^ in the first three 

 pairs of per^eopoda in some families of Isopoda, and 

 is probably most strongly developed in the first pair 

 of Squilla and other Stomatopods. 



The next step in the development of these 

 organs is represented in many genera, as for in- 

 Fig. 50 The first pair of ^^^^^^^ j^^ ^^^ sccond pair in S i mo r hy n ch o t u s, the 



first pair in Streets i a (fig. 52), the first pair m 

 Dorycephalus, the first and second pairs in Tullbergella (fig. 51), 

 and in others, that is to say: 



2. The subcheliform hand, (fig. 51 — 5o) in which the carpus is broadly 



dilated backwards, but not produced downwards, 

 or only very little produced, so that the meta- 

 carpus impinges against the under margin of 

 the carpus, the dactylus here coming in contact 

 with the hind margin of the carpus. When the 

 hind margin of the metacarpus is in contact 

 with the under margin of the carpus, the meta- 

 Fiy. 51. The first pair of ^arpus is at a right angle with the axis of the leg, 

 Tullhergella cuspidata. the leg being supposed to hang straight down. 



Fig. 52. The first pair of 

 Streetsia Steentrmn. 



Fig. 53. The first pair of 

 Cranocephalus Goesi. 



The next form, the most developed prehensile organ, is best re- 

 presented in the second pair of perasopoda in the genus Oxycephalus 

 (fig. 54), but is also met with in the first pair in the same genus, in the 

 second pair in Streetsia (fig. 55), and in others; that is to say: 



