8 DR. W. BAIRD OTf! A NEW BRITISH ANNELTDE. 



that the siugulax' bony enlargements on the posterior face of the 

 sternum and in the bumps or knobs at the sternal edge, as seen in 

 the drawing sent, mark the ultimate development of the trachea ; 

 whilst the state of the trachea in the sternum sent by Sir John 

 Eichardson to Mr. Tarrell, and which I now assign to C. Pass- 

 mori, may be a less advanced form of the same structure, and 

 those I have since examined may be still younger forms of the 

 same species. 



" It may be, indeed, that the specimens since examined are 

 younger specimens of G. Passmori, and that the true C. hiiccinator 

 is less common, or at least a more northern form ; but I think it 

 right to indicate the doubt which I feel myself respecting the 

 new species, leaving the facts for the consideration of better 

 judges. I thought I followed excellent authority in considering 

 such a difference in the trachea as a sufficient mark of a distinct 

 species ; but the facts will not be less interesting to ornitholo- 

 gists if they see reason for using such characters Avith greater 

 caution in future. At present, I must leave the value of my dis- 

 tinctions as a subject for further inquiry, with as little wish to 

 press an unnecessary specific name as to leave interesting facts 

 unrecorded. 



" W. HiNCKs." 



Description of a new British Annelide, belonging to the Tribe 

 Rapacea of (jrv\ibe= Annelida errantia of Milne-Edwards. By 

 W. Baird, M.D., F.L.S. 



(Plate I.) 



[Eead April 21, 1864.] 



Fam. NEEEIDID^. 



G-en. Heterokereis. 



HETEROIirEREIS SIGNATA, Baird. (PI. I. figS. 1, 1 «-C.) 



Char. Corpus pyramidatum, maculatum, dorso et ventre canaliculatum. 

 Segmenta 2°dumj 3rtium^ 4tum et Sn*"™ brevissima ; segmenta sexdecim 

 sequentia magna, pedibus validis, simplicibus ; segmenta partis poste- 

 rioris corporis parva, confertim disposita, pedibus parvis, compositis; 

 cirri pedum anteriorum simplices, non crenati. 



liah, Polperro, Cornwall ; in fundo limoso. (Mus. Brit.) 



The body of this Annelide (PL I. fig. 1) is nearly 3 inches 

 long, consisting of about 106 segments. The anterior portion is 



