^ : Fam. 3, Plate 42. 



PROGTONOTIJS MUCRQNIJJERUS, Alder and Hancock. 



'■i •'• ' '. ■ ' 



P. ovatus fulviflus," brunnep-marjtno>atus :'- '-branchiis ovatis, hyalinis, tuberculatis, in seriebus 12, 

 utrinque ad marginem' dorsi dispositi^V-papillis 4, magnis, frontalibus : tentaculis dorsalibus sub- 

 tuberculatis. ( ' ^: '- \ -.*■ '• 



Venilia mucrpnifera, % A\di.' and Hanc. in Ann. Nat. Hist. v. 13, p. 161, pi. 2. 



Proctonotus mucroniferus,- Aid. and Hanc. in Ann. Nat. Hist. v. 13, p. 407. 



Hab. In shallow* water, Malabide Bay, near Dublin. 



Body nearlyl\half an inch long, ovate, rather broad and depressed, subtruncated in 

 front, and produced behind into a long pointed tail; the sides flattened or concave, 

 projecting in a ridge above. The back is slightly rugose, of a pale yellowish brown colour, 

 clouded and freckled with darker brown, and covered with minute opake white spots ; the 

 rest of the body is hyaline white, nearly colourless, having a few small brown spots on the 

 head and sides, and more numerous opake white ones over the whole surface. Head with 

 a semicircular veil, strongly notched in front, and bearing two short cylindrical tentacles at 

 the sides. Dorsal tentacles of a purplish brown colour, with darker freckles, rather long, 

 stout, and slightly conical, irregularly wrinkled and somewhat tuberculated; their bases 

 nearly approximate, the points stand apart and are inclined forwards. Eyes rather large 

 and placed as usual. Branchiae ovate or inversely pear-shaped, produced into blunt and 

 flattened apices, and haying large, rather distant tubercular points over the whole surface. 

 They have a crystalline appearance, being very transparent and nearly colourless, sprinkled 

 with opake white spots. The central vessel is small and not half the length of the papillae. 

 It is yellowish, granular, and elliptical, tapering to a slender duct below. The branchiae 

 are set along the projecting ridge on each side of the. Back, in twelve transverse rows of 

 three very close-set papillae each ; those next the back large and inflated, the exterior ones 

 very small; two larger than the rest are placed posteriorly;,^ These lateral rows are united 

 anteriorly by four large, elliptical, tuberculated papillae,/. apparently of a similar nature with 

 the others, which pass round the head in front of the-., dorsal tentacles, and alternate with 

 five smaller ones below. Foot rather broad and ,,oV8?te,, tapering to a fine point behind, 

 transversely grooved and bilobed in front, but not produced into angles; it is pellucid, with 

 a portion of the gastric system seen through, yellowish*,.^ ahd minutely spotted with opake 

 white. \ ,' 



A single perfect specimen of this curious animal, and another much injured, were dredged 

 up in Malahide Bay, in September, 1843, adhering to a sponge (Halichondria panicea) 

 from rather shallow water. The first lived with us for two or three weeks. It turned 

 sickly soon after it was caught and lost several of its larger papillae : some of these were 

 afterwards reproduced and grew very rapidly ; but the papillae on the front of the head, 

 which were amongst those that had fallen off, never reappeared, so that we were prevented 



