329 



the regular order of differentiation of the somites from before back- 

 wards is preserved, the retarded appearance of the posterior thoracic 

 appendages shows the beginning of the process which has led to the 

 suppression of these somites and appendages in the typical Zoea. 



NOTES ON HABITS, ETC. 



The Stomatopoda are exclusively marine, the adults generally 

 inhabiting burrows in the sand or mud of the sea-bottom in shallow 



Fio. 193. 



Larva of the second Kriehthus-tyys (the Pseuderichthus group). ', antennule ; a", antenna ; 

 a, first pleopod ; 6, uropod ; ep, epipodite ; I, II, first two pairs of thoracic appendages. 

 (After Glaus, from Korschelt and Heider's Embryology.) 



water (up to 180 fathoms), chiefly in the tropics, but extending 

 north to Britain and Japan, and south as far as Auckland. Many 

 species seem never to wander far from their burrows, into which 

 they retreat with great rapidity when alarmed, and are thus seldom 

 obtained by the ordinary methods of collecting. The larval stages, 

 on the other hand, are exclusively pelagic, of glass-like transparency, 

 and occur in great numbers in the plankton of the warmer seas. 

 All the Stomatopoda appear to be of active, predatory habits. The 

 range in size within the group is about from 38 to 340 mm. 



