vol.i.] Tprrey. — Hydroida of the Pacific Const. 1!) 



12. Stem polysiphonie at base only; principal branches simple 



E. ramosum (p. 34) 



13. Unbranehed Atractyloides formosa 6 



13. Branched 14 



14. Gonophores fixed sporosacs Bimeria 15 



14. Gonophores free medusae Perigoniinus 19 



15. Stem polysiphonie 16 



15. Stem simple 17 



16. Stems several inches long, robust B. robusta (p. 29) 



16. Stem less than an inch long B. nutans' 



17. Stems annulated throughout B. annulata (p. 28) 



17. Stems not annulated throughout 18 



18. Hydranth with 10-12 tentacles B. gracilis 6 



18. Hydranth with 14-16 tentacles; hydrorhiza creeping over base of 



stem B. franciseana (p. 28) 



19. Branches not annulated ; tentacles 4-12 P. repens (p. 29) 



19. Branches slightly annulated; tentacles 10-16 P. (?) formosus 5 



20. Tentacles filiform; fixed sporosacs Clavidae 



Hydrocaulus rudimental; hydranths claviform ; gonophores prox- 

 imal to tentacles Clava 21 



20. Tentacles capitate Corynidae 22 



21. More than 20 tents. ; color red Clava leptostyla (p. 30) 



22. Gonophores free medusae Syncoryne 23 



22. Gonophores fixed sporosacs; tents, of one sort Coryne 24 



23. Tentacles 20-30; colony 2 or more inches high S. eximia (p. 31) 



23. Tentacles 16; colony \ in. to li in. high S. mirabilis (p. 31) 



24. Branches regularly annulated throughout C. braehiata' 2 



25. Hydrothecae saucer-shaped; hydranth with conical proboscis 



Haleciidae 26 



25. Hydrothecae campanulate, pedunculate, with partial septum at 



base Campanulariidae 33 



25. Hydrothecae tubular, without basal septum, margin smooth, no 



operculum Lafoeidae 60 



25. Hydrothecae well developed, sessile; nematophores absent 



Sertulariidae 66 



25. Hydrothecae well developed, sessile, borne on one side of stem or 



branch only; nematophores present Plumulariidae 92 



26. Gonophores medusoid Campaleeium 27 



26. Gonophores fixed sporosacs Halecium 28 



27. Rim of hydrotheca strongly everted; hydranth with 24-28 ten- 



tacles; gouophore with 4 tentacles C. medusiferum (p. 48) 



28. Non-fascicled 29 



28. Fascicled 32 



29. Annulated :in 



29. Not annulated 31 



30. Hydrothecae usually half as deep as broad; gonothecae very much 



compressed H. annulatum (p. 49) 



30. Annulated or corrugated, unbranehed or irregularly branched; 



about 20 tentacles H. corrugatum 7 



30. Sparsely and irregularly annulated: irregularly branched: para- 

 sitic; 23-30 tentacles H. ornatum- 



