CHAPTER III. 



THE HABITS AND METAMORPHOSIS OF GONODACTYLUS CHIEAQRA. 



By W. K. Brooks. 



(With PI. I, III, XIV, and xv.) 



The Structure and Habits of the Adult. 



This well-known species is t'outid alou;^ the shores and islands of all tropical and subtropical 

 seas, and our collections contain si)eciiiions from tlie Atlantic, the Pacific, and the Indian Oceans. 

 Among the many localities where its presence has been recorded the following may be named: 

 Bermuda, Florida Keys, Bahama Islands, Cuba, St. Thomas, Brazil, Mediterranean, Cape St 

 Iloqne, iSaniboanga, Samboanga Banks, Nicobars, Bed Sea, Auiboina, Indian Ocean, New Gninen. 

 It is subject to but little variation, notwithstaudiug its ver.y wide distribution, and also notwith- 

 standing the fact that there are several other distinct species of Gonodactylus extremely similar 

 to chiragra, and distinguishable from it by only very minute differences. There is a well-marked 

 ehiragra-like group of species all so close to each other that their divergence from each other must 

 have been comparatively recent, and in view of this fact it seems remarkable thaf one of these 

 spe<;ies should so persistently retain its identity when exposed to such a wide diversity of 

 conditions. 



The species may be thus characterized : Stomatopoda with the sixth abdominal somite sepa- 

 rated from the telson by a movable joint; the hind body convex; and the dactyle of the raptorial 

 claw without spines and enlarged at the base ; rostrum consisting of a transverse proximal portion 

 more than twice as wide as long, with subacute antero lateral angles and a slender, acute median 

 spine which does not quite reach to the bases of the eyes ; carapace nearly rectangular, three lifths 

 as long as wide, leaving the dorsal surface of the second thoracic somite completelj' exposed ; au- 

 tero-lateral angles semicircular and projecting beyond the median gastric area, which is nearly Hat, 

 and bounded by two nearly parallel gastric sutures, which are continued to the posterior edge of the 

 carapace, which is nearly transversa with rounded posterolateral angles; the transverse cervical 

 suture is faintly marked, distaiic from the anterior margin about two-thirds of the length of the 

 carapace; secoiul thoracic sonflte, somewhat narrower than the carapace, with acute lateral angles; 

 the eight following somites ecpnil in width and wider than the carapace; the third, fourth, aiul 

 tifth thoracic somites about e()ual in length ; the lateral margins of the third are straight, with 

 rounded angles, and as wide as the dorsal jiortion ; the fourth is narrowed a little towards the 

 lateral edge, and the fifth still more so ; dorsal surfaces of the free thoracic somites and of the first 

 five abdominal somites smooth ; hind body <!onvcx ; all the abdominal somites have marginal lateral 

 cariuic, which are nearly linear, with the anterior end only a little wider than the posterior end; 

 posterolateral angles rounded in the first four abdominal somites, rectangular in the fifth, and 

 acutely pointed in the sixth; there are no dorsal carina* on the first five abdominal somites, and 

 no median dorsal (carina on the sixth, which carries three pairs of swollen convex lateral carinie, 

 which are equal in length and end posteriorly in acute spines, which are occasionally wanting 

 on the submedian pair; the external carina is much less swollen than the others, and it unites 

 at its posterior end with the laterial marginal carina; the spines of all the carina project bejond 



the posterior edge of the somite and lie in the same transverse plane. 



353 

 S. Mis. 94 23 



