zoorimi- 29 



H mi nliit r<l anil very irregularly branched Tliey are not more than 1 mm. in 

 ilia meter. 



The hydrothecae are elongated and everted at the margins. They are 

 frequently reduplicated. 



The hydranths are 0'5 mm. in length and have alxiut 20 tentacles 0'25 mm. 

 in length. There arc no nematophnres in this species. 



(jonotvmt 1 . The gonothecte are oval (0'8 x 0'5 mm.) or spherical in lx>th 

 - \. -. T!ir\ BM -ilu. >;.'! OB -l.-i: ptdfodi u ; i-!i nny Dt iii'L'nlailv ;iiniiil.i!.-.! M 

 in the British type. They are situated on the hydrocauli in no definite position. 

 There is no evidence of any " coppinia "-like grouping of the gonothecae. 



The species Ifaltvium tenelluin was obtained by the ' Belgica ' expedition in 

 70 S. by 91 W., and Bale mentions that he has one specimen in his collection 

 from the Australian waters. It has also l)een found on the south Fuegian coasts 

 and in Smyth Sound (10 : pp. 505-509). It is common on the British and 

 American coasts and extends into the Arctic seas (Jan Maycn). In fact, it appears 

 to be cosmopolitan in Arctic and Temperate seas. 



SUB-FAMILY LAFOKINAE. 

 LAFOKINA LONOITHECA. 



(Plate IV., fig. 31.) 

 Lafonna longitheta, Jiderholm, Arch. Zool. Expdr. (4), III. (1904), p. iv. 



Locality. McMurdo Bay, February 20th, 1902 ; 5-20 fms. 



Two small colonies of this hydroid were found creeping on the free hydrorhixa 

 of /'. / -iif<mimw> anfarcticu*. 



lly<lroome. A well-developed hydrorhizal filament is attached to the support. 

 From this there arise at intervals tall, cylindrical hydrothecaj (fig. 31) O'7-l'O mm. 

 in height, slightly annulated at the base, and gracefully everted at the margin. 

 The margin bears about twelve opercular flaps (fig. 31, op.), O'll mm. in length. 

 Occasionally secondary hydrothecte arise from the primary ones and attain an 

 additional length of 0'25 mm. There is no distinct pedicel, the diameter of 

 the hydrotheca at the base being almost great as it is at the distal extremity. 



The hydranths are very small, being in the contracted condition not more than 

 0*4 mm. in length, or about half that of the hydrotheca A circlet of about eight 

 tentacles surrounds the blunt conical hypostome. Each tentacle is about 0*13 mm. 

 in length. 



Numerous upright nematophores, 0'12 mm. (but occasionally 0'2 mm.) in height 

 by 0'02 mm. in diameter, arise independently from the hydrorhiza. They contain a 

 delicate thread of tissue (fig. 31, d.), terminating in a pad at the extremity which 

 is armed with a battery of nematocysts. 



Gonosoins. Not observed. 



