Calkins. -- Hydroids. 
PLATE 6. 
Variations in the diaphragm. 
Fig. 6d. Campanularia jolinstoni. Diaphragm prolonged to form a tube 
around the coenosarc. 
Fig. 8d. Campanularia inconspicua. An elevated ridge on the diaphragm. 
Fig. 9d. Campanularia attenuata. Diaphragm with small wing-like elevations. 
Fig. lOd. Campanularia gracilis. 
Fig. lid. Campanularia caliculata. 
Fig. 12f. Campanularia integra. 
Fig. 13d. Obelia gracilis. 
Fig. 14c. Obelia surcularis. 
Fig. 15c. Obelia fragilis. 
Fig. 16e. Obelia dichotoma. 
Fig. 18d. Obelia griffini. 
Fig. 20d. Calicelia syringa. 
Fig. 23b. Obelia plicata. 
All figures magnified 375 diams. 
All figures drawn with camera lucida from permanent preparations. 
