ART. 10 LAKVAE OF GEAPSID CRABS HYMAN. 5 



SECOND MEGALOPS (fig. 25). 



The second megalops stage differs from the first chiefly in the 

 shape of the cephalothorax. The carapace is shorter, broader, and 

 more depressed. The frontal spine has disappeared and its position 

 is marked by a furrow. 



Cephalic appendages. — The antennule (fig. 29) shows three en- 

 larged basal segments bearing distally the two palps. The endopo- 

 dite is composed of five segments each bearing sensory hairs. The 

 exopodite has two segments, the distal bearing hairs. The antenna 

 (fig. 29) is a single flagellum. The proximal three segments are en- 

 larged. The mandible, the maxillule (fig. 36a), and the maxilla 

 are (fig. 41) scarcely changed from the first megalops condition. 



Thoracic appendages. — (Figs. 44, 47, 49, 50, and 52.) These show 

 only a few minor changes. 



Abdomen. — The abdomen is appreciably broadened and flattened. 

 The appendages (fig. 54) are fully developed as swimming organs. 



FIRST CKAB STAGE. 



In the first crab stage the cephalothorax has the definite quadrate 

 shape of the family. It is greatly depressed. The abdomen is 

 permanently flexed under the sternum. The periopods are large 

 and flattened. 



Cephalic appendages (figs. 30, 365, and 42). — The exopodite of 

 the antennule has disappeared and this appendage as well as the 

 remaining cephalic appendages is in the adult condition. 



Thoracic appendages (figs. 45, 48, and 53). — These are now in the 

 adult condition. 



Abdomen. — The megalops abdominal appendages are present but 

 are small and shriveled. The adult appendages have not yet de- 

 veloped. 



PLANES MINUTUS (Linneaus). 



The zoea of this species was known to Thompson who writes that 

 it so closely resembles the zoea of Eriphia caribbea as not to merit 

 a separate description or figure. The zoea probably does not occur 

 regularly in the tow at Beaufort. The ovigerous female from which 

 were hatched the specimens here described was brought into the har- 

 bor by an unusual combination of wind and tides on June 22, 1920. 



The zoea is notable for its minute size (0.9 mm. long and 0.3 mm. 

 dorso-ventrally through cephalothorax), its disproportionately large 

 eyes and long maxillipeds, and its heavy pigmentation. 



FIRST ZOEA (figs. 1 and 2). 



Cephalothorax. — The dorsal and rostral spines only are present 

 and each is slender and rather short (0.2 mm.). The pigment spots 



