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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. XXVI. 



Albuneids seem to be present at one time, and the question naturally 

 arises, is this their normal proportion, or do they occur in greater num- 

 bers in some more favored locality, perhaps farther out where the 

 sands are not always in motion, and where they would be able to use 

 more deliberately, in feeding, the hands which have been altogether 

 denied their rehitives, the Hippids; or do they live deeper in the sand, 

 where their long antennuL-v may not only warn them of the presenc(' 

 of prey, but keep the way open and even entice the victim within 

 reach of the strong hands ^ The answer to this question must be 

 deferred until collectors have recorded more careful and extended 

 observations; and it may not be out of place to here suggest 

 that one reason for the scarcity of individuals is that collectors, 

 having quickly obtained a sufficient number of 

 Hippids for their purposes, do not prolong the 

 search, and so miss a chance to obtain the rarer 

 Albuneids. Between these forms striking differ- 

 ences will be observed. The Hippids are shuttle- 

 shaped, while the Albuneids, except in the case of 

 Blepharijjoda, are broader across the front than 

 anywhere else. To some difference in habit is pos- 

 sibly due the great difference in the eyes. Those 

 of the Hippids are on slender almost thread-like 

 stalks, while those of the Albuneids are remark- 

 able for the peculiar and diverse shapes of the 

 stalks which furnish characters that may be used 

 not only to distinguish the genera, but to quite an 

 extent, even the species in a genus. In the genus 

 Alhunea they are flattened, elongated, and in most 

 species acutely triangular in shape, with a small 

 cornea at the apex. • In the genus Lepidopa they 

 are scale-like, and in some species almost rec- 

 tangular, while the cornea, if the small speck 

 can be so called, may be situated either on the 

 terminal or lateral margin. It is hard to under- 

 stand just what is the function of the broad scale-like stalk. The speck 

 which serves for the eye can hardly do more than distinguish lioht 

 trom darkness. In the genera having mere eyespecks on a scale- 

 like stalk the antennulfe are extraordinarilv developed. This forces 

 another question upon us: Is not this a case of one sense organ hav- 

 ing been developed at the expense of or in compensation for another, 

 tor the antennulffi are sense organs of no slight power, being from 

 two to live times the length of the carapace-straight, stiff, and well 

 provided with hairs which are probably sensorv. These organs must 

 ^ be more useful than eyes to an animal living submerged in the sand 

 -Jn the situations where they have been found. Bhphcmpoda has yet 

 aditterent eyestalk, slender as in the Hippids, but jointed in the middle. 



Fig. 1.— .Vntexnulae of 

 Lepidopa myops, x i. 



