SUPER-ORDER IV CIRRIPEDIA 649 
that these Cirripedes pass through a nauplius stage, and that directly before 
attachment both Balanus and Lepas undergo a Cypris-stage, thus showing very 
clearly their relation to the Eucrustacea. 
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 (Coronula, 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 (Scalpellum, Verruca). Many of 
the living families are naked, and naturally only those possessing shells 
(Thoracica) have left fossil remains, although some of the tubular cavities in 
mollusecan 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 caleare- 
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 serves 
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. 

Fic. 1355. 
- Lepidocoleus Sarlei, Clarke. 
es. ; ; ilurian; Rochester, N 
Family 2. Turrilepadidae. Clarke. Bee Dorsald MEL and 
ventral views. 
Body with four to six vertical 
columns of triangular plates, two of the columns being small, 
accessory, and sometimes much modified in shape. Caudal plate 
patelliform, axial. 

Fic. 1356. 
Turrilepas Wrightianus, de Turrilepas, Woodw. (Plumulites, Barr.), (Fig. 1356). Body 
Koninek. Silurian; Dudley aA as 2 = C 7 5 
Wigland: A, Complete indi: elongate-conical with four to six columns of large triangular 
vidual, 1. B, C, Isolated overlapping scales, some of which are keeled in the middle. 
plates, enlarged (after Wood- : é ; ‘ 3 ae li 1 
ward). Besides having concentric striae, surface may be radially linec 
or punctated. Cambrian (?) to Upper Devonian. 
Strobilepis, Clarke. Composed of four columns of overlapping plates, two of which 
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 
