THE BURROWING BARNACLES (CIRRIPEDIA: ACROTHORACICA ) 21 



aged "Higgins Eternal Ink" or bone charcoal powder had been 

 added, at 13°C in semidarkness. On day three, four females were 

 removed from the ink-water, killed, and sectioned. On day four, 

 sixteen of the remaining animals were placed in IK inches of clear 

 sea water at IS^'C, and samples were removed, killed, and sectioned 

 at intervals stated in the table below. On day seven, the barnacles 

 from the bone charcoal were kiUed. All barnacles were living upon 

 removal from the test conditions. 



The sectioned barnacles were grouped rather subjectively into five 

 classes, numbered 0-4, but judged on the following basis: — no 

 carbon; 1 — a trace of carbon; 2 — a little carbon; 3 — some carbon; 

 4 — considerable carbon. The sUdes were judged by serial number 

 only, without the bias of knowing how long the animal had been in 

 the solutions. The largest portion of the stomach was used as a 

 standard point of judgment. 



Table 1. — Results from the ingestion and egestion of carbon particles in Trypetesa 



lateralis. 



Number in classes 

 Number of females Days in ink Days in clear water 12 3 4 



* Bone charcoal carbon. 



Conclusions: Under ideal conditions for a complete elimination 

 at one time, one would expect all specimens to be in grades "0" and 

 "4." The difficulties of this statement have already been stated: 

 the carbon can be reingested after eUmination into the mantle cavity 

 and still not reach stages 3 or 4, or the female may not have reached 

 stages 3 or 4 in the first place. A complete spasmodic elimination would 

 fit the data as well as a gradual elimination. 



The only statement that can be made is that apparently there is 

 regurgitation, but whether it is spasmodic or gradual cannot be 

 determined from this type of data. The regurgitated material is not 

 compacted into pellets or ribbons. 



Excretory System 



The excretory system of the acrothoracicans, as maxillary glands, 

 does not dijffer in essential features from that of the thoracicans. The 

 system has been reviewed by Utinomi (1960) and Nilsson-Cantell 

 (1921). Four species from different families have been investigated in 



