54 MARINE POLYZOA. 



1. DlACHORIS CROTALI. PI. LXVI. figs. 1, 2. 



Cells erect, open in front, with straight sides ; perforated on 

 the sides and bottom ; a lanceolate appendage articulated to each 

 upper angle. Ovicell small, conical, superior. 



Diachoris crotali, Busk, Voy. of Rattlesn. 382. tab. i. figs. 10, 12. 

 Hab. Bass' Stijait. 



The frond, although, as explained above, not strictly adnate, 

 as it seems to have no attachments, is usually spread loosely over 

 other Polyzoa. There is no appearance of a moveable mandible 

 in the lanceolate appendages, which nevertheless most probably 

 represent avicularia. These organs are of a lanceolate form, with 

 an elevated ridge or keel along the back, and slightly concave 

 beneath : they project in front, slightly depending, and at the 

 base of each is a rounded eminence. 



2. DIACHORIS MAGELLANICA. PL LXVII. 



Cells semi-erect, open in front, oval ; mouth circular with a 

 thickened and raised margin. A pedunculate and articulated, capi- 

 tate avicularium attached to the margin of the cell near the top 

 on each side. Ovicell ?. (Frondose, with cells on both sides, 

 and also loosely adnate.) 



Hab. Straits of Magellan, Darwin ; New Zealand, Lyall. 



3. DIACHORIS INERMIS. PI. LXXII. 



Cells decumbent, boat- shaped, entirely open; two short mar- 

 ginal spines on each side near the top. Ovicell ? Avi- 

 cularium ? 



Hab. New Zealand, Lyall. Straits of Magellan, Darwin. 



This species approaches very nearly to a Membranipora, and 

 from the total absence of any moveable appendages, might per- 

 haps be regarded as a type of a distinct genus : as, however, it is 

 a solitary instance of the form, and agrees in the structure of the 

 polyzoary with the above two species, it has been associated with 

 them and not with the Membraniporidse. 



