JÄDERHOLM, EXOTIC HYDROIDS IN THE SW. ZOOL. STATE MUS. 7 



description given by Nutting as also with a fragment of the 

 original specimen of S. Torreyi, kindly sent me by the author. 

 The abcauline walls of the nearly immersed hydrothecae mea- 

 sure 0,384 — 0,416 mm in length and the free adcauline portion 

 about 0,096 mm. The breadth of the hydrothecae is 0,224 — 

 0,256 mm. Marginal teeth four, slightly indicated. 



Locality: East India, Paumben, 1 — 5 fathoms, x4pr. 1889 

 (Dr. K. Fristedt.) — Dr. W. M. Bale has kindly drawn my 

 attention to the fact that under the name of Sertularella 

 tridentata Lmx. two different species are associated, namely 

 S. lata (Bale), and 8. diaphana (Bitsk, Allm.). The hydroid 

 which I ha ve described in a previous publication^ under the 

 name of Sertularella tridentata Lmx. is identical with S, lata 

 (Bale). 



Sertularella formosa Fewkes Pl. 2, Fig. 3. 



Locality: The Pacific Ocean, Pearl Islands, South of 

 Panama, 6 fathoms, Vg 1882 (Dr. C. Bowallius). Three 

 sterile fragments ha ve been brought home. 



Plumularia bidentata n. sp. Pl. 2, Fig. 5 — 6. 



Stems from a creeping hydrorhiza, erect, about 25 mm in 

 height, unbranched, monosiphonic, of a brown colonr, with 

 oblique joints divided in internodes of variable length. The 

 breadth of the stem in the proximal portion about 0,122 mm. 

 Hydrocladia pinnately disposed, slender, alternate, rather clo- 

 sely set, of a paler colour than the stem. Their internodes, 

 separated by oblique joints, 0,330 — 0,376 mm in length, about 

 0,038 mm in breadth. Each internode bears one hydrotheca, 

 two lateral and two median sarcothecae. Hydrothecae, borne 

 on processes from . the proximal ends of the internodes, adnate 

 to the hydrocladia, with horizontal apertures and anterior 

 outlines everted. Margins provided with two very large teeth, 

 opposite each other, which are strongly bent outwards. The 

 length of the hydrothecae measures 0,094 mm and the breadth 

 at the mouth about 0,085 mm. Three short träns verse folds 

 of the hydrothecal internodes are developed. The lateral 

 sarcothecae, trumpet-shaped, 0,056 — 0,065 mm long, reaching 

 to the top of the teeth. Median sarcothecae, trumpet-shaped, 



^ JJLDKRHOLM, E., Hydroids from the South Seas, Norrköping 1917, 

 pag. 13. 



