508 



CRUSTACEA MALACOSTRACA. 



obscure function, on the inner margins of the first pair of 

 abdominal feet. 



The ovary extends throughout the thorax and abdomen and 

 like the testis is unpaired behind and paired in front. The 

 oviducts converge to closely approximated openings in a median 

 depression on the 5th thoracic segment, a small receptaculum 

 seminis being situated between the orifices. On the sterna of 

 the three following segments are cement glands. 



Development. Our information on the earliest stages of 

 the development of Stomatopods is imperfect. The eggs are 

 small ( - 6 mm. in one species), but the form in which the young 

 larvae are hatched is, in several genera, unknown. In some 

 species at any rate the eggs are deposited by the mother in a 



burrow, and are 

 there aerated by 

 currents of water 

 produced by her 

 r espiratory 

 movements. 



The larvae are 

 elegant, trans- 

 parent creatures 

 which lead a 

 pelagic existence 



Flo. 310. A Metanauplius larva regarded as the predecessor of and. Undergo a 

 the Erichthoidina stages (after Lister). B The youngest known i i 



Erichthoidina larva (after Hansen). a', a" first and second marked m 6 t a - 

 antennae ; abd first abdominal legs ; c./ caudal fork ; p.l.s and i -p 



p.m.s postero-lateral and postero-median spines ; r (in B) morpnoSlS. 56- 



rostrum. . ,-, , 



fore their rela- 

 tion to adult Stomatopods was recognized they received generic 

 names, two of which, Erichthus, and Alima, havs been retained 

 to distinguish two somewhat different types. 



The earliest (Erichthoidina) stage of the Erichthus type, whose 

 connexion with succeeding stages has been traced, is comparable 

 though not closely with the Protozoea stages of other forms 

 (Fig. 311 A). A large cephalic shield, folded over at the sides, 

 is produced into anterior and posterior median and into postero- 

 lateral spines. The larva possesses a median and two well 

 developed lateral eyes and five biramous swimming thoracic 

 appendages of which the second is as yet only slightly the largest. 

 Though all the thoracic segments are formed the three posterior 



Heart* 



tbd 



li 



