226 CONTRIBUTIONS TO MARINE BIONOMICS. 



Zoolofiy, I, p. 158), but he did not apparently publish his observations 

 in full until 1865. 



In the meantime Mr. David Eobertson communicated to the Philo- 

 sophical Society of Glasgow, on March 13th, 1861, an interesting note 

 on the function of these antennae. He described the burrowing habits 

 of the crab, and shewed that, under these circumstances, the antennal 

 tube preserved " a free passage for the purpose of enabling the animal 

 to carry on the process of its aqueous respiration." Mr. Robertson 

 believed, with Gosse, that the current through the tube was exhalent in 

 character. In another paper he stated that " he had seen the ova cast 

 up through the opening [of the antennal tube]- — the inference being 

 that the animal had placed it by means of its claws within the influence 

 of the current." {Proc. Nat. Hist. Soc, Glasgoiu, vol. i. p. 1.) 



Gosse (1865) similarly observed that each antenna, from the form and 

 arrangement of its bristles, constituted a "semi-tube, so that when 

 the pair was brought face to face the tube was complete." He also 

 carefully watched a living specimen, as it was sitting upright on the top 

 of the sand, close to the side of a glass aquarium, and observed that 

 the antennal tube formed a channel for a definite current of water. To 

 quote his own words : " I immediately saw that a strong current of 

 water was continuously pouring up from the points of the approximated 

 antennse. Tracing this to its origin, it became evident that it was pro- 

 duced by the rapid vibration of the foot-jaws, drawing in the surrounding 

 water, and pouring it off upwards between the united antenna?, as 

 through a long tube. ..." "I think, then, that we may, with an 

 approach to certainty, conclude that the long antennae are intended 

 to keep a passage open through the sand, from the bottom of the burrow 

 to the superincumbent water, rendered effete by having bathed the gills ; 

 and it is one of those exquisite contrivances and appropriations of 

 structure to habit which are so constantly exciting our admiration . . . 

 [and] are ever rewarding the research of the patient observer." 



We shall see below that while Gosse's conduit- theory of the function 

 of the antennae is perfectly correct, his inferences as to the function of 

 the antennal conduit are true only to a limited extent. Gosse assumed 

 that the habits of the crab when beneath the sand were similar to its 

 habits when above the sand, and confined his observations to the crab 

 in the latter condition. Experiment shews, however, that there may be 

 a marked difference in the working of certain organs under the different 

 conditions. 



A third theory as to the function of the antennae in Corystcs 

 cassivelaumis is due to Mr. A. R. Hunt (1885). He says, " I incline to 

 think that the function of the antennte is to maintain a communication 

 between the buried crab and the water above, as without some such con- 



