﻿10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 59 



surface of the sand. Garstang (loc. cit.) says, "It seems to me not 

 unlikely that further observation of the habits of Hip pa talpoida 

 [ = Emerita talpoida] of the American coasts will reveal an essentially 

 similar sieve-like function for the curiously bent and setose second 

 antennas of that animal ". Emerita, however, as might be expected, 

 shows a very close correspondence with its congener Albunea, the 

 antennules and not the antennae forming the respiratory tube. 



Before considering in detail the mechanism of respiration in 

 Emerita, it will be well to describe the animal's normal position in the 

 sand. If a specimen of Emerita analoga is placed in a dish containing 

 sand and water it will usually bury itself at once until the rostrum is 

 just below the surface of the sand. Here while the body is concealed, 

 the antennules and slender eye-stalks may be seen projecting above 

 the surface. Occasionally it buries itself more deeply at first, but 

 usually comes to rest in the position described. If the antennules are 

 carefully examined it will be seen that they extend vertically from the 

 sand, the four flagella making the angles of a square prism, while the 

 space between them forms a sort of canal free from sand which is 

 excluded by the interlocking hairs which each flagellum sends out 

 toward its neighbor (figs. 3 and 6, pi. 1). If some powdered carmine 

 or India ink suspended in sea water is allowed to flow from a pipette 

 near the antennular tube, it will usually be drawn down the tube show- 

 ing an inhalant current. Occasionally the current will be found to 

 set in the opposite direction, and if an animal resting upon the sur- 

 face of the sand is examined, this will be found to be the normal direc- 

 tion. Here the water is drawn in at the sides of the carapace, as may 

 readily be shown by experiment. 



A closer examination shows the presence of very complete channels 

 for the conduction of water to the gills. The single respiratory 

 channel inclosed by the four branches of the antennules turns, at the 

 bases of the latter, ventrally into a chamber inclosed between the 

 bases of the antennae laterally, the bases of the antennules dorsally, 

 and the expanded ciliated tips of the exognaths of the first and second 

 maxillipeds ventrally. Passing back, the channel is divided by the 

 raised and overhanging apex of the triangular labrum, and now lies 

 to either side, enclosed laterally by the pterygostomian plate and 

 ventrally by the exognath of the first maxilliped. In this canal is 

 found the leaf-like scaphognathite. 



The use of such a respiratory apparatus is obvious. While the 

 animal is buried, an adequate supply of water free from sediment 

 may be obtained from above the surface of the sand when the wave 



