106 



CCELENTEBATA 



Fig, 174 — Sertularia pumila 



(Nutting). A, portion of 



a colony ; B, a gonangium. 



1. Sertularia L. Hydrothecae in pairs along the stem, the mem- 

 bers of a pair being exactly opposite each other; operculum paired 

 (Fig. 173, A) ; gonangia have plain margins and are of simple form: about 

 20 American species. 



S. pumila L. (Fig. 174). A simple or more or less branched colony 

 1 to 5 cm. high attached by a creeping hydrorhiza, the stem being divided 



into short internodes, each bearing a pair 

 of hydrothecae; gonangia oval, sessile and 

 often bearing acrocysts, the male gonan- 

 gium being somewhat more slender than the 

 female : common on f ucus, etc., between tide 

 lines, from New Jersey to the Arctic Ocean ; 

 California; Europe. 



2. Sertularella Gray. Similar to 

 preceding genus, but differs from it in that 

 the hydrothecae are alternate on the hy- 

 drocaulus and not opposite, and possess a 

 prominent operculum composed of several pieces; gonangium usually 

 deeply annulated: about 50 American species. 



Key to the species of Sertularia here described : 

 Oi Margin of hydrotheca with 4 slight teeth. 

 6i Hj'drotheca annulated. 



Ci Annulations only on upper side S. GAYI 



Cz Annulation complete S. rugosa 



62 Hydrotheca smooth S. polyzonias 



03 Margin of hydrotheca with 3 teeth S. tbicuspidata 



S. rugosa (L.) (Fig. 175). A small colony 2 cm. high, either un- 

 branched or little branched and with annulated stem; hydrothecae 

 crowded, annulated and with 4 marginal teeth; gonangia 

 large, annulated and with four-toothed aperture: New 

 England coast; Puget Sound; Europe. 



S. gayi (Lamouroux). Colony attaining a height of 

 15 cm. and with paired or alternate branches; hydrothe- 

 cae wrinkled or partially annulated and with a four- 

 toothed aperture; gonangia elongate, ovate, tapering 

 towards both ends, annulated in upper portion : Atlantic 

 coast; Europe. 



S. polyzonias (L.). Irregularly branching colony 

 attaining a height of 12 cm. ; hydrotheca smooth, with 4 

 teeth; gonangium deeply annulated and with 4 teeth: Atlantic and 

 Pacific coast; cosmopolitan; common. 



S. tricuspidata (Alder). Colony 12 cm. high or less and slender ] 

 with alternate branches; hydrotheca smooth, with 3 teeth; gonangium 



Fig. 175 



Sertularella 



rugosa 

 (Kingsley), 



