HALICOEXARIA SPECIOSA. 55 



margin with wide, rather shallow crenation ; intrathecal ridge springing from 

 the anterior side of the hjdrotheca about midway between the margin 

 and base, and extending transversely to about the middle of its lateral 

 walls. Supracalycine nematophores stout, overtopping the margin of the 

 hydrotheca ; mesial nematophore reaching ihe margin of the hydrotheca, 

 and adnate to it in nearly its entire length. 



Gonosome. — Gonangia cylindrical, with a broad, truncated summit, con- 

 tracted below into a short, stout latero-basal peduncle, which springs 

 from the front of the stem close to the origin of a pinna. 



Double-Headed Shot Key, from a depth of from 4 to 5 fathoms. 



Halicornaria speciosa is a strong, handsome species. The pinnae are abso- 

 lutely lateral, showing no disposition to arise from the anterior aspect 

 of the stem. The stem is unusually thick for a monosiphonic or non- 

 fascicled form, and each of its internodes carries four nematophores, one 

 just above and one just below the point of origin of the pinna at each 

 side. 



The gonangia in the specimen are small in proportion to the size 

 of the trophosome, and are possibly immature. 



