Fam. 3, Plate 43. 



Genus 10. ANTIOPA,* Alder and Hancock. 



Corpus ovato-oblongum, postice acuminatum. Caput subinferius, velo parvo obtectum. Maocillm 

 cornese. Tentacula 4, quorum 2 majora, dorsalia, et 2 minora labialia. Tentacula dorsalia laminata, 

 basibus cristse arcuatee centrali conjunctis. Branchice papillosse, ovatse, utrinque ad marginem lateralem 

 et prominentem dorsi dispositse, et anterius circum caput collocatse. Anus posticus, in linea media 

 dorsi situs. Apertura genitalis ad latus dextrum. 



The principal character which induces us to consider this genus distinct from Proctonotus 

 is the remarkable crest between the dorsal tentacles, a character so peculiar as apparently to 

 warrant a generic distinction. The lamellated form of the tentacles, and the length and bifid 

 termination of the glands of the papillae, may possibly prove to be of generic importance ; but 

 from our present imperfect" knowledge of these animals, confined in each genus to a single 

 species, and in Proctonotus to a single perfect specimen, we can scarcely determine the value 

 of these characters, nor the extent of their variation, with any degree of certainty. The 

 genus was first described by M. Verany of Genoa, in the 'Revue Cuvierienne,' for 1844, 

 under the name ot Janus, & name previously appropriated by Mr. Stevens to a genus of 

 Hymenopterous insects in 1835. At the time when we proposed for it the generic appellation 

 here adopted,! we had not the means of ascertaining its identity with the Janus of M. Verany, 

 which we have since had ample opportunity of doing through the kindness of that 

 distinguished naturalist; but, adopting the views expressed in the rules for zoological 

 nomenclature, published by the British Association, as to the propriety of discarding duplicate 

 names, we have retained the name of Antiopa in preference to that of Janus, which, under 

 other circumstances, would have been entitled to priority. 



The body in this genus is ovate, rather depressed, and tapering to a point posteriorly. 

 It has a produced ridge on each side assuming the appearance of a rudimentary cloak. The 

 dorsal tentacles are laminated, non-retractile, and united at the base, and for a short way up, 

 to an arched fleshy crest. The head is inferior, subangular in form, and without a veil, but 

 having the margin of the lips projecting considerably, with two small linear or cylindrical 

 oral tentacles. The mouth is provided with strong horny jaws, and a broadish denticulated 

 tongue. The branchiae are papillose and elongated, arranged round the head and down each 

 side of the back, nearly meeting behind. At their posterior termination, a median ridge runs 

 down to the tail. The anus is situated posteriorly on the median line of the back, a little in 

 advance of the termination of the branchiae. It is tubular and conspicuous. The foot is 



* A classical proper name. 



t Ann. Nat. Hist., 2d series, v. 1, p. 190, 



