APPENDIX. 



The following note on the extraordinary genus Herpa, from 

 the Guilding MSS., and referred to in the text, is too valu- 

 able to be omitted. 



HERPA Guilding. 



Animal terrestre, pulmoniferum. Corpus molle, subgelati- 

 nosum, raucrone obductum, elongatum, contractile, depressum, 

 antice praesertim attenuatum. Os apicale, minutissimum, 

 obscurum. Fades contracta, emarginata. Tentacula nulla. 

 Scutum nullum. Oculi cervicales. Solea magnitudine corporis, 

 nee distincta. Glanduke plurimae ventrales mucorem ab ore 

 transverso efiuadentes, unica majore central!, equa viscus lo- 

 batum, molle, plicatile, parvulum, rare protruditur. 



Genus valde distinctum, et inusitatae formaa. Corpore fere 

 toto erecto Herpa more serpentum prolabitur, viam mucore 

 superillinens, et tentaculis carens cervice longo valde attenuate 

 vestigia diriget. Genus Planariis facie quam plurimum analo- 

 gum, ut Limacibus respirationis modo, locis, moribusque 

 omnino affine. 



In the 8th number of the Zool. Journ. p. 443. a short notice 

 of this genus was given, drawn from a single specimen which 

 must now be struck out. The capture of many of them has 

 enabled me materially to improve the description. They are 

 very singular animals, and in their external characters have a 

 remarkable resemblance to the Planarice, which, however, as 

 Cuvier observes, inhabit only salt or fresh water, and therefore 

 can have no relation of affinity with Herpa. Probably, the PL 

 terrestris and Candida of Gmelin may resemble them in their 

 economy. I have found the Herpes on the decayed fronds of 

 D D 3 



