ANTHOZOA 137 



E. crassa Edwards and Haime. Colony up to 50 cin. high and half 

 as broad; diameter of trunks 8 to 15 cm.; coenenchym thick, corky: 

 West Indies. 



2. PLEXAURELLA Kolliker. Colony arborescent; trunks cylindrical; 

 axis horn-like and calcareous; cup edges smooth; coenenchym usually 

 very thick. 



P. dichotoma Dana. Stem 12 to 20 mm. thick; branches smooth, 

 club-shaped; color brownish: West Indies; very common. 



SUBORDER 4. PENNATULACEA.* 



Sea pens and sea feathers. Colony not fixed, but capable of inde- 

 pendent movement and consisting of two parts, a stalk which is im- 

 bedded in sand or mud, and an upper part called the rachis, which bears 

 the polyps and may have the form of a feather, a rod, a broad plate; a 

 central calcareous or horn-like axis usually present ; outer layer of mesoglea 

 permeated with spicules forming a crust; polyps 

 large and in communication with one another by 

 entodermic canals and dimorphic, the autozooids 

 being of ordinary structure, the smaller siphono- 

 zooids having no tentacles or gonads and reduced 

 mesenteries and serving for the inflow and outflow 

 of water through the entodermal canals : 15 families 

 and over 200 species. 



FAMILY 1. PENNATULIDAE. 



Sea feathers. Rachis elongate with paired lat- 

 eral branches or pinnulae; siphonozooids confined 

 to lower side of rachis : about 4 genera. 



PENNATTJLA Lamarck. Pinnulae long, from 20 

 to 50 in number on each side, bearing the autozooids 

 on their upper margin: several species. 



P. aculeata Danielsen (Fig. 223). Length 10 

 cm.; rachis with numerous spines among the sipho- 

 nozooids ; color deep red, stalk rose-colored, becom- FI s- 223 

 ing whitish at the base: Gulf of St. Lawrence to Pennatui^aculeata 

 Carolina, in 100 to 500 fathoms; common; Europe. 



P. grandis (Ellis) (P. borealis Sars). Length up to 50 cm.; color 

 orange; breadth 14 cm.: Newfoundland to Nantucket, in 100 to 600 

 fathoms. 



* See "Die Pennatuliden," by A. Kolliker, Frankfort, 1870. 



