THE SESSILE BARNACLES. 57 



tlie posterior ramus protuberant. Besides the usual long spines, tlie 

 distal borders of the segments bear minute multifid scales. 



CuTus ii has 15 and 12 protuberant segments, posterior ramus 

 shorter by 5 segments. 



Cirrus iii is about one-thu'd longer than ii, with rami of 14 and 13 

 somewhat protuberant segments, the posterior ramus shorter by 4 

 segments. They have series of short, erect spinules along the distal 

 borders of the segments. 



CuTi iv to vi are nearly similar, composed of a gieat number of 

 short segments, which bear three pairs of long and a fourth of short 

 spines. Tliere are tufts o*" small spines on the anterior edge, between 

 the spines of the pairs. A regular row of erect spinules borders each 

 segment distally, wanting on some of the ill-defined bnisal segments. 

 The antorior distal angles of the pedicel are also spmulose. The 

 median segments of ciiTus vi are about twice as wide as long (fig. 

 9a). Cirnis vi is about 23 mm.- long. 



Balanus tintinmihdum tintimiahuluin (Lmnreus) is known in North 

 American waters only as a frequent immigrant on ships. I do not 

 know that it has anywhere established itseK in our faima, but we 

 have no knowledge of tlie barnacles of the Gulf ports, where such 

 introduction would be expected to occur, if anpvhere. The natural 

 habitat of the race remains to be defined, and the inquuy is difficult, 

 because specimens from ports all over the world find their way into 

 nmseums, v/ithout data showing whether they are part of the local 

 fauna or from ship's bottoms; moreover, it is likely that some forms 

 recorded as vai\ communis will prove to be separable races. It has 

 not been found in any Antillean or North American Tertiary or 

 Pleistocene deposits. 



Figures 1 — le and the above description were drawn from speci- 

 mens taken from a ship which arrived at Philadelphia from Hongkong 

 and Java. They were associated with B. t. zebra and B. t. occator, 

 but no intermediate or transitional forms were seen. The cylindrio 

 fonn with larger orifice is prevalent in otlier lots, particularly those 

 standing crowded. 



The United States National Museum contains numerous specimens 

 referred to B. t. tintinnabulum, chiefly collected from ships m English 

 and American ports; others from tropical localities and New Zealand 

 are without opercular valves, and therefore of uncertain subspecific 

 identity. 



BALANUS TINTINNABULUM ZEBRA Darwin. 



Plate 10, %g. 2 to 8. 



1854. Bulanus tintinnabulum, var. 2<;&?-a Darvv-in, Moiioi^Ta])]!, etc., p. 195, ])1. 1, 

 fig- ^• 



Form conical or somewhat tubular ; livid purple or dark livid purple, 

 with snow-white ribs ; radii wide, colored ; slieatJi madder hrown. Sum- 



