BRITISH NUDIBRANCHIATE MOLLUSCA. 53 



1. F. nobilis, A. and H. Buff or whitish; tentacles long, tapering, both pairs similar; branchiae 

 crowded, with the central vessel dark brown, and an opaque iridescent apex. Length 2 

 inches. PI. 38a, Jig. 1. 



Genus 16. HERJVLEA, Lov£n. 



Without cloak. Branchiae papillose, set on the sides of the back. Tentacles 2, 

 ear-shaped. Anus antero-dorsal. Appendix (37), p. xii. 



Tongue, a single plate hearing a broad spine. No jaws. 



Section 1. Tentacles with both margins terminating at the sides of the head; body 

 cylindrical. 



1. H. bifida, Mont. Yellowish-white, with 2 red lines along the back, slender; tentacles rather 

 short, truncated, rising in a point behind; branchiae oblong, slightly tuberculated, with a 

 ramified rose-coloured vessel in the centre of each. Length 1 inch. PI. 39. 



Section 2. Tentacles with the anterior margin continuous with the side of the head, forming 

 a sub-veil ; body with the sides depressed and slightly expanded. 



1. H. dendritica, A. and H. Greenish-white with dendritic green veinings ; tentacles oblong 

 ear-shaped ; branchiae elliptic-linear, green, spotted with white. Length ^ inch. PI. 40. 



Genus 17. ALDERIA, Allman. 



Without cloak. Head with two lateral lobes or rudimentary tentacles. Branchiae 

 papillose, set in transverse rows on the sides of the back. Anus postero-dorsal. 



Tongue a single plate with a large central spine. No jaws. 



1 . A. modesta, Loven. Yellowish, variegated with brownish-gray ; branchiae elliptical, set in 6 or 8 

 rows, increasing in size posteriorly ; foot large, reflected at the sides. Length | inch. 

 PI 41. 



Sub-Fam. Proctonottn^. Tentacles 4, non-retractile, without sheaths, oral pair small. Branchiae 

 papillose. Anus postero-dorsal. Posterior vessel of the gastro-hepatic system central. 



Genus 18. PROCTONOTUS, Alder and Hancock. 



Branchiae arranged on an obsolete pallial ridge, on the sides of the back and in front of 

 the head. Dorsal tentacles simple, linear. Oral tentacles originating in a veil. 

 Tongue broad, with numerous spines. Corneous jaws. 



1. P. mucroniferus, A. and H. Fawn-coloured, marbled with brown; branchiae inflated, hyaline, 

 mucronated, set in 12 rows on a pallial ridge on the sides of the back, with 4 large ones in 

 front. Length i inch. PI, 42. 



