162 Mr. C. Spence Bate on the Nidification of Crustacea. 



poda), which are used only to seize prey and convey it to the 

 mouth. 



" The tube is always proportioned to the size of the animal, 

 and appears to invest it closely ; nevertheless, when the animal is 

 prevented from proceeding onwards, it turns its body immediately, 

 protrudes its head from the opposite extremity, and thus makes 

 use of either end indiflferently as the anterior part. 



"When swimming about, one-half of the body is projected from 

 the tube, and is suddenly and repeatedly inflected, so as to pro- 

 ceed forwards by jerks." 



We thus perceive that Say was on the verge of a very inter- 

 esting discovery in the habits of the small Crustacea, but, yield- 

 ing to analogous facts, fell short of arriving at the truth. 



Mr. Templeton, in the 1st volume of the Transactions of the 

 Entomological Society, describes a Crustacean of the same genus 

 which he observed likewise to dwell within a tube, and which 

 he named Cerapus abditus. 



Alluding to another species of this genus, Mr. Stimpson says, 

 in his ' Marine Invertebrata of Grand Manan,' " The Cerapus 

 rubricornis inhabits flexible tubes, of sizes corresponding to those 

 of the individuals, composed of fine mud and some animal cement 

 by which it is agglutinated. These tubes are generally adherent 

 for about one-half their length, and closed below. They are 

 usually found in large groups, attached to submarine objects 

 and to each other. The animals are very active, protruding and 

 retracting the anterior portion of their bodies, while their an- 

 tennae are in continual motion, lashing about in search of some 

 object which might serve for food. It is very amusing to watch 

 a colony of these animals, with their comical gestures in their 

 disputes with each other, and their awkward celerity in regain- 

 ing their respective tubes after having left them on temporary 

 excursions. I have in no instance met with an individual trans- 

 porting a free tube, as is said by Mr. Say to be the case with his 

 C tubularis. There can be no doubt but that the tube is fabri- 

 cated by the animal ; and this is not without precedent in the 

 Crustacea, for I have often met with examples of Pagurus which 

 had enlarged their borrowed shells by additions to their aper- 

 tures*. From what I have seen in such species of Corophiidce as 

 have fallen under my observation, I am inclined to think that 

 most of the members of that family form more or less permanent 

 tubes under certain circumstances. The Unciola, when kept in 

 captivity, will frequently retire to some corner, and collect the 

 sand around it by some glutinous substance so as to form a 

 cavity, in which it will often remain for some time ; but it may 



* These additions are the result of a sponge growing upon the shell, 

 and not built by the Crab.— C. S. B. 



