THE BURROWING BARNACLES (CIRRIPEDIA: ACROTHORACICA) 5 



a considerable distance, especially upon drying, and empty-appearing 

 tapered slits in all sheUy material should be examined, using the 

 following procedures. Note is made of the shape of the burrow in the 

 shell before all cirripeds are removed. Individual identification is 

 indicated as more than one species of cirripeds can occupy a single 

 shell or coral fragment. It is standard practice to photograph the slit 

 with the photographic axis perpendicular to the surface of the shell, 

 and mth a small piece of graph paper as a scale in the field of focus, 

 for later reference if the specimen contained within the slit is a new 

 species or is otherwise of special interest. If enough specimens are 

 available, study should be made of the internal shape and size of the 

 burrow, the presence of males on the wall of the burrow, and the 

 extent of the cemented attachment area of the female. This is best 

 done by chipping away one wall of the burrow and removing the 

 female without the aid of acid, although many useful observations 

 can be made after the shell has been decalcified. 



It will be noted under the section on the Burrow (page 9) that the 

 shape and size of most species varies more within some species than 

 between several genera, so at present the burrow shape is a useful 

 taxonomic char'^.cteristic only in distinguishing between families. 



Most of the shelly material should be decalcified in a weak acid 

 solution to aid in the removal of the specimens. If the specimens are 

 obtained alive, they can be nicely fixed and the shell decalcified at 

 the same time by placing them in a large quantity of Bouin's fluid. 

 If the specimens are processed in formahn or alcohol, additional acid 

 can be added at intervals to decalcify the shells. If the specimens are 

 dried, they can be placed in 70-percent ethyl alcohol with 2-percent 

 HCl. The alcohol preserves the specimens when they are decalcified; 

 but 10-percent formahn is satisfactory, and even water can be used 

 if the barnacles are removed quickly. 



There is no special concentration of acid to use. Specimens have 

 been placed in grossly different concentrations of hydrochloric acid 

 for days without ill effects, and other acids work mth similar ease. 

 Carbon dioxide bubbles form below the specimen and Uf t the specimen 

 from the burrow when the shelly matrix is sufficiently decalcified. 

 These bubbles could perhaps damage the specimen if they are formed 

 too violently. It has been found that an initial concentration of 1- to 

 2-percent HCl is most effective, with HCl added at intervals to keep 

 the bubbling action at about the initial level. 



Most specimens will not be completely freed from the shelly matrix, 

 and must be hunted out and removed by gently puUing or tearing 

 apart the decalcified matrix. The dark red coloration on the barnacles, 

 which is retained in most species through the above treatment, aids 

 in locating them; dental tools or watchmaker's forceps aid in their 



