4 PROCEEDINGS OF THE NATIONAL, MUSEUM, VOL.65 



The antenna (fig. 28) shows a, finger-like bud, the endopodite, the 

 anlage of the future flagellum. 



The mandible (fig. 31) bears an unsegmented smooth palp. 



The maxillule (fig. 34) shows the solitary epipodital hair on the 

 basipodite. The appendage now reaches its greatest differentiation. 

 Its palp is composed of two segments, and it carries seven or eight 

 long hairs. 



The maxilla (fig. 39) also reaches its greatest differentiation. Its 

 palp carries six to nine hairs. 



Thoramc appendages. — The first and second maxillipeds show 

 twelve and eleven swimming hairs respectively. The third maxil- 

 Jiped does not have hairs and is rudimentary, but all of its segments 

 are differentiated. 



The periopods are rudimentary, although all of their segments are 

 differentiated. The first bears two gills, the second and the third 

 one each. 



Ahdomen. — The third, fourth, and fifth segments bear short lateral 

 spines on their posterior margins. The sixth segment is separated 

 from the telson. All the segments except the first carry bifurcated 

 appendages. These are smooth as yet. 



FIRST MEGALOPS (fig. 24). 



Cephalothorax. — The body has the usual shape of a brachyuran 

 megalops. The dorsal spine has disappeared without leaving a trace. 

 The frontal spine is reduced in size but still prominent. The perio- 

 pods are well developed. 



Cephalic appendages. — The antennules and antennae are not de- 

 scribed by Cano by word or drawing. The mandibular palp (fig. 

 32) shows three segments and carries sensory hairs. The maxillule 

 (fig. 35) is considerably altered. Its palp has begun to degenerate. 

 Its joints are lost and it carries a single hair. The maxilla (fig. 39) 

 also has begun to degenerate. Its palp is hairless. The scaphog- 

 nathite is larger. 



Thoracic appendages. — The maxillipeds (figs. 43, 46, and 51) show 

 the usual megalops condition. The exopodite becomes a sense organ 

 and develops a palp terminally. The endopodite is greatly enlarged 

 and with the basal segments becomes an organ of mastication. Gills 

 appear upon the second and third maxillipeds. 



The periopods are greatly enlarged and well-formed. They appear 

 elongated and slender and are nearly cylindrical. 



Abdomen. — The abdomen is depressed. Ihe appendages are not 

 mentioned by Cano but they probably are typical for the stage. 



The telson becomes a flattened plate with a rounded posterior 

 border. 



