SUPER-ORUKU IV 



649 



that these Cirripedes pass through a nauplius stage, and that directly before 

 attachment both Balamis and Lepas undergo a Cfyprw-stage, thus showing very 

 clearly their relation to the Eiicrustacea. 



All Cirripedes are marine animals. Those with calcareous shells attach 

 themselves to stones, wood, mollusks, crabs, corals, and sea plants, and often 

 cover rocky coasts in myriad numbers. Some genera (('<>n>nnl>i, Chenolobia) 

 embed themselves in the thick skin of whales and dolphins ; some (Pyrgoma, 

 Palaeocreusia) bore into corals or shells of mollusks, and others lead a parasitic 

 existence in the abdominal cavity of Decapods or within the shells of other 

 Cirripedes. Most barnacles inhabit shallow water, but certain genera occur 

 at great depths, from 1900 to 2000 fathoms (Sealpellum, J'<mica). Many of 

 the living families are naked, and naturally only those possessing shells 

 (Tlioracica) have left fossil remains, although some of the tubular cavities in 

 molluscan shells may have been perforated by naked Cirripedes. Fossil 

 forms occur sparingly in the older strata, and do not become abundant until 

 near the close of the Tertiary. 



Order 1. THORACICA. Darwin. 



Body indistinctly segmented, and enclosed in a membranous mantle in which calcare- 

 ous plates are usually developed. Mostly hermaphroditic, sometimes with complemental 

 males. 



Family 1. Lepidocoleidae. Clarke. 



Body covered with two vertical columns of overlapping plates, those of one series 

 alternating with those of the other. Terminal or caudal plate axial. Basal or cephalic 

 portion of the body with a ventral curvature. Apices of the plates on the dorsal margin. 

 No accessory plates. 



Lepidocoleus, Faber (Fig. 1355). Elongate, blade-shaped ; 

 dorsal edge the thicker, ventral edge sharper and linear. The 

 two series of plates make a complete enclosure, being inter- 

 locked on the dorsal edge, but are only in apposition on the 



ventral edge, where they were un- 



doubtedly capable of dehiscence for 



the protrusion of the appendages. 



Most primitive genus of the group. 



Ordovician to Devonian. 



FlG 1355 



M >""' ; . Clark.-. 



Family 2. Turrilepadidae. Clarke. 



ventral views. 



FIG. 1356. 

 Turrilejxis Wrightianus, de 



Body with four to six vertical 



columns of triangular plates, two of the columns being siitnll, 

 accessory, and sometimes much modijied in shape. Caudal plate 

 patelliform, axial. 



Turrilepas, Woodw. (Plumulites, Barr.), (Fig. 1356). Body 

 5 il com n p ie?e U Si- elongate-conical with four to six columns of large triangular 

 vicinal, i/j. ' R, c, isolated overlapping scales, some of which are keeled in the ini<Mli-. 

 plates, enlarged - Begideg h aving concentric striae, surface may be radially lined 



or punctated. Cambrian (?) to Upper Devonian. 



Strobilepis, Clarke. Composed of four columns of overlapping plates, two of winch 

 are of large and equal size. Of the other two intervening columns, one consists of a 

 few very small plates, and the other is modified into a series of grooved spines which 



