166 A new species of Terrestrial Planaria. [No. 34, 



The genus Herpa determined by the late Rev. Lansdown Guilding* 

 in the West Indies is evidently a kindred form. Swainson, misled 

 by a desire to carry out his theory, eagerly caught at this discovery, 

 and saw in it the first incipient development of the order of Phytopha- 

 gous or pulmonary molluscs. -j- He even adopted Herpa as the first 

 genus of his sub-family Limacinse, making Onchidium a subgenus 

 with Herpa proper. The common species of Onchidium^ so common 

 in the Oarnatic, and which may often be found in the same haunts 

 with our Planaria, will prove at once, to the most superficial observer, 

 the anomalous character of this arrangement ; the Onchidium being 

 furnished with eyes, feelers, mouth, a mantle, a perfect internal sys- 

 tem of respiration^ and circulation, and complicated digestive and 

 sexual organs. 



* Zool. Journal, No. viii. p. 443. 



Animal^ terrestrial, respiring by means of pulmonary vessels [pulmoniferum.] 

 Body soft, sub -gelatinous, drawn to a point, elongated, contractile, depressed, 

 much attenuated, anteriorly. Mouth at the extremity [apicule] — very minute, in- 

 distinct. No ientacula. No mantle. Foot the extent of the body, not well defin- 

 ed. With numerous ventral glands discharging a mucous secretion through trans- 

 verse openings, and with a single larger one in the centre, from which a lobed cup 

 [viscus] is rarely protruded, which is soft, pliable, and rather small." 



" This genus is well marked and of a most unusual form. The Hei*pa glides 

 along with the greater part of the body erect like a serpent, marking its track with 

 slime, and directing its course, in the absence of feelers, by means of its long neck, 

 greatly attenuated [or extended."] 



*' I have found the Herpae on the decayed fronds of palms, on the summits of the 

 highest mountains, and on the dry lands within a few yards of the sea : these 

 always seeking cool places for concealment during the day, but never approaching 

 the water, which, upon being thrown into, they instantly quit." 



Mr. Guilding discovered three species in the West Indies, the largest of which, 

 B. gigas^ was 6 or 7 inches long. The only individual of the species, captured by 

 him, escaped through a small crevice of the box in which it was placed, " from the 

 strange power it possesses of contracting its body," — Swainson. Ajppendix. 



+ Lardner's Cab. Cycl. Malacology, pp. 161, 189. 



♦ Guilding indeed in speaking of Herpa observes, " Genus Planariis facie quam 

 " plurimum analogum, ut Limacides respirationis modo, locis moribusque, omni- 

 <* no affine." If the respiratory organs were indeed satisfactorily detected Herpa 

 must be placed in a higher grade of the animal kingdom. But Guilding's des- 

 cription answers in all other respects so exactly to Planaria — terrestrial examples 

 of which have been met with subsequently by Darwin and others in South Ameri- 

 ca, Maui'itius, Van Dieman's Land, New Zealand and other countries — that it is 

 probable he was deceived in assigning this character. Duges and Darwin suppose 

 that the respiratory functions are exercised by means of vibratile cilia or some ana- 

 logous structure disposed along the inferior surface or foot of the animal — Annals 

 of Nat. Hist. , Y. xiy. p. 243. 



