66 



NATURAL HISTORY OF ARTHROPODS. 



greatly condensed. There are two 

 types of development, one passing 

 through the forms which were for- 

 merly considered as adult, and de- 

 scribe4 as Erichthus and Squiller- 

 ichthus, the others through an 

 Alima stage, with the probabilities 

 that the former represents the larva 

 of GoRodactylus, the latter certainly 

 that of Squilla. In the youngest 

 known M-ichtJius tj'pe we have 

 both stalked eyes and a single 

 median ocellus, while the first ten 

 pairs of apjtendages are developed, 

 the sixth to tenth being bifiagellate. 

 Behind these arc three segments of 

 the body without ajjpendages. A 

 large carajiax covers the anterior 

 portion of the body, and is pro- 

 longed into a spine in front. After- 

 ward the last three maxillipeds be- 

 come aborted, and then grow out 

 again in their permanent form. 

 The abdominal feet develop in suc- 

 cession from before backward, and 

 all are fully formed before the ap- 

 pendages of the three posterior tho- 

 racic segments appear. In the Alima type of devel- 

 opment, wliieh has been followed through by Profes- 

 sor Brooks, it seems probable that the young leaves 

 the egg in nearly tlie Alima form, and in the yomigest 

 stage known the six appendages, eight to thirteen, are 

 absent, although three of the corresponding segments 

 of the body are develojied, while the abdominal seg- 

 ments and their appendages are well developed. None 

 of the thoracic members are biramous. From this, 

 which corresponds to the Erlditltvs after the atrophy 

 of the appendages, a regular development produces 

 the adult form. 



There are two well-marked genera of Stomatopoda, 

 Hquilla and Gonodactylus, the former being divided 

 into several sub-genera. Thirteen species of the 

 Squillidse are found in American watci's, Squilla ein- 

 pusa extending as far north as Newport, IM., where 

 it burrows in the mud, forming large irregular holes. 

 The colors are very bright, — green, red, yellow, and 

 black predominating. The large pincer in both genera 



• (■ 1 1 j-1 1 * • • 4. £ 4.1 1 i- 1 T 4_-L Fig. 83. — Advanced larva of 5(7«i//ae»i- 



is formed by the last joint oi the leg tokUug upon the pu^a, enlarged. 



Fig. 82. — Squilla empui^a, mantis slirimp, reduced. 



