264 



BBYOZOA 



Family 3. CRISTATELLIDAE. 



Colonies forming compact hyaline groups which secrete a gelatinous 

 base; aperture slightly elevated above the level of the group; statoblasts 

 large, about 1 mm. in diameter, provided with hooks : 2 genera. 



Key to the genera of Cristatellidae: 

 Oi Statoblast with a row of marginal hooks; gelatinous base often very 



thick 1- Pectinatella 



02 Statoblast with 2 rows of marginal hooks ; gelatinous base forms a thin 



sole 2. Cristatella 



1. Pectinatella Leidy. Many associated colonies in rosette-shaped 

 groups on a gelatinous base which may attain a 

 thickness in the autumn of 40 cm.; the youthful 

 colony is locomotory: 1 American species. 



P. magnifica Leidy (Fig. 435). Tentacles 60 to 

 84 in number; statoblasts circular, black in color, 

 with 10 to 22 marginal anchor-shaped hooks: often 

 common on stones, sticks, etc., in ponds and streams; 

 North America; introduced locally into Europe and 

 Japan. 



2. Cristatella Cuvier. Colony an elongate, 

 gelatinous mass with a thin, flat sole on which it 

 creeps; the zooids are located on the upper surface 

 of the colony and may contract into a common cavity; 

 statoblasts circular with 2 rows of marginal hooks: 1 

 species. 



C. mircedo Cuv. (C. idae Leidy; C. ophidioidea Hyatt; 

 C. lacustris Potts) (Fig. 436). Young colony circular, 

 later elongate, attaining in the autumn a length of 28 

 cm. ; usual length 3 to 5 cm. ; 80 to 90 tentacles ; statoblasts 

 with 10 to 34 hooks in one row and 20 to 50 in the other: 

 America and Europe, in ponds and sluggish streams on submerged sticks, 

 pond lily leaves, etc.; not common. 



Fig. 435 — Pectina- 

 tella magnifica (Dav- 

 enport). A, a thick 

 gelatinous mass sur- 

 rounding a stick on 

 whicli are numerous 

 colonies ; B, stato- 

 blast. 



Fig. 486 



Statoblast of 



Cristatella 



mucedo 



(Sussw. F. 



Dent.). 



SuBPHYLUM 5. BRACHIOPODA. 



Sessile, marine, mollusk-like animals in which the body is enclosed 

 in a bivalve, calcareous, or homy shell, one valve of which is dorsal and 

 one valve ventral. Tlie shells (Fig. 437) can be opened and closed by 

 means of muscles, the hinge end being posterior and tlie opening anterior 



* See "Catalogue of the Recent Species of the Class Brachiopoda," l)y W. II. Dall, 

 Proc. Acad. Nat. Sci., Phil., IST.*?, p. 177. "A Monograph of Recent Brachiopoda," by 

 T. Davidson, Trans. Lin. Soc, 2nd ser., Vol. 4, 1S80-1888. "Revision of the B^amilies 

 of Loop-bearing Brachiopoda," by C. E. Beecher, Trans. Conn. Acad., Vol. 9, 1893. 



