AXOMURA. 



289 



In individual cases, the metamorphosis is slightly abbreviated, the larvae 

 first hatching as Mctazoacae. This is the case in Galathodes and in the genus 

 Lithodes, which is closely related to the Paguridae. In both these forms, the 

 eggs are comparatively large, and the escaping larvae take with them into 



larval life considerable masses of yolk, at the expense of which 

 their further development is accomplished. In consequence of this, 

 the mouth -parts of Galatlwdes (like those of Palaemon Potuina, 

 mentioned above, p. 274) remain for some time in a remarkably 

 undeveloped condition ; they are truncated and have no setae. In 

 both these forms, the development of the sixth pair of pleopoda 

 (uropoda) seem to be retarded as compared with that of the 



FIG. 134. Metazoaea of Hippa talpoidea (after S. SMITH), mf, mf", mf", the 

 three maxillipedes ; pi-pf^, rudiments of the first four ambulatory limbs. 



other abdominal limbs. A much greater reduction of the meta- 

 morphosis is found in Birgus latro, if the statement of WILLEMOES- 

 SUHM, which rests on the report of a fisherman, is established, 

 according to which the young of this species leaves the egg in a 

 form very similar to that of the adult. 



The larvae of Munida, whose metamorphosis in all important 

 points agrees with that of the typical Anomuran described 

 above, are distinguished by a greater develop- 

 ment of the spines. The rostrum exceeds in 

 length the rest of the dorsal shield, the two 

 posterior tips of the latter are drawn out into 

 long spines, and the deeply -cleft telson also 

 runs out into two long spinous processes. 



An excessive development of spines is found 

 in the Porcellana larva (Fig. 135), which has 

 long been known as Lonchophorus (EscHSCHOLz), 

 whose development, excluding older accounts, 

 has been made known by MULLER (No. 140), 

 DOHJIN (No. 121), GLAUS (No. 8), FAXON (No. 

 126), and G. 0. SAKS (No. 150). The frontal 

 spine is here of quite unusual length. The two 

 lateral spines also, which end like hooks and 

 run out posteriorly, are of considerable length. 

 The telson has here no posterior incision, but 

 is a rhomboidal plate. In a few points, the 

 metamorphosis of Porcellana approaches that of the crabs, viz., in the position 

 of the abdomen, which is ventrally curved, and hi the order in which the 



FIG. 135. Metazoaea of 

 Porcellana longicornis 

 (after G. O. SARS). mf, 

 mf", mf", the three 

 maxillipedes ; p, rudi- 

 ments of the ambula- 

 tory limbs and their 

 gills. 



