PODOPHTHA LMIA . 65 



similar habit of burrowing, but is much quicker in its motions. Our common Ocypoda 

 arenaria is fond of " beach fleas " (Amphipoda), which it catches by lying in wai^; 

 and springing upon them, very much as a cat catches mice. 



Fjg. 81. — Gelasimus pugillator^ tiddler crab, natural size. 



In the tropical regions of the globe are found the true Land Crabs, Gecarcinid^, 

 which spend almost their entire life away from the water, only going to the sea at the 

 breeding season. At all other times they fi-equent the mountains, running with great 

 rapidity at the approach of an enemy. 



Okdee IV. — STOMATOPODA. 



The most important characters which separate this from the other orders of 

 Podophthalmia may be briefly stated as follows : The carapax is smaller than in the 

 Decapods, the first antenrial and the last or last three or five of the thoracic rings 

 being perfect and uncovered by the carapax. The ambulatory and raptorial feet are 

 seven in number, the two external maxillipeds of the Decapoda here being enlarged 

 and losing their functions as mouth-parts, thus showing an approach to the Edrioph- 

 thalmia. The five anterior pairs of these feet are furnished with an imperfect pincer, 

 the last joint closing upon the preceding one. These three posterior feet are aU 

 bifurcated or schizopodal in character. In the gills also we notice important features, 

 for these organs instead of being carried upon the bases of the thoracic feet, and pro- 

 jecting into a respiratory chamber, are borne upon the first five pairs of abdominal 

 feet, and hang freely in the water. The heart, instead of being a small and compact 

 thoracic organ, as in the Decapods, here is a long, slender tube, extending the length of 

 the abdomen. The principal venous sinus, as would be inferred from the location of 

 the gills, is also abdominal. The nervous system is formed upon the usual arthropodal 

 type, and the abdominal ganglia are united by double commissures, which have not 

 been united as in the Decapods. 



The early phases of the development of the Stomatopoda have not been studied. 

 The eggs are laid in burrows in the bottom of the sea, and from this to the AUma 

 stage nothing is known. Fritz Mllller, Glaus, and Professor W. K. Brooks have 

 studied the development of this order from this point on, the results of which are here 



