Fam. 3, Plate 44. 



Figs. 8 to 12. 

 ANTIOPA HYALINA, Alder and Hancock. 



A. elliptica, postice attenuata, pellucida, pallide lutescens, rufescenti-fulvo longitudinaliter in 

 medio dorso notata; branckiis ellipticis, tuberculatis, hyalinis, glandula centrali fulva, lineari; 

 tentaculis dorsalibus linearibus, obtusis, obscure laminatis; velo capitali arcto, tentaculis 2 brevibus 

 instructo. 



Hab. Hilbro Island, mouth of the Dee, Cheshire, J. Byerley, Esq. 



Body three tenths of an inch in length, elliptic-oblong, very transparent, yellowish, with 

 reddish brown markings. Dorsal tentacles rather short, linear, a little curved backwards, 

 obtuse and rounded above, with about ten oblique rather obscure laminae, reaching very close 

 to the apex ; yellowish fawn-coloured, spotted with brown and white. They are united at 

 the base by a semicircular crest of the same colour, with transverse lobules, giving it a 

 radiated structure at the sides. The crest rises to about one third the height of the tentacles. 

 Oral tentacles very short, linear-conical, set on a narrow semicircular veil that surrounds the 

 head. Back pale transparent yellow, thickly spotted and blotched down the centre with 

 bright reddish brown. Brancldce numerous, elliptic-oblong, tapering to a blunt point, and 

 tuberculated or mucronated on the upper part. They are of a hyaline transparency, showing 

 a rather stout fawn-coloured central vessel, reaching about two thirds up. The surface is 

 spotted with brown and opaque white, with blotches of the latter on the tubercles. The 

 branchiae are densely arranged on a pallial ridge down the sides of the body, and round the 

 head, without forming regular rows. They meet behind the anus, concealing the posterior 

 extremity. Foot strongly grooved in front, with the lateral angles rounded. It tapers to a 

 point behind. 



This interesting mollusk was obtained by Mr. Byerley when dredging at the mouth of 

 the Dee in the summer of 1851. Though a true Antiopa, from the laminated tentacles and 

 dorsal crest, this animal shows a very close approach to Proctonotus mucroniferus in the 

 tuberculated branchiae and small frontal veil. Its colour, too, reminds one a good deal of 

 that single known species of Proctonotus. Reviewing the two genera again, since the 

 acquisition of this species, we find no character to distinguish them from each other but the 

 dorsal crest, and laminated or unlaminated tentacles. The former feature, however, is so 

 peculiar that we still feel ourselves justified in keeping them apart. 



The spawn forms a cylindrical cord, loosely convoluted like that of Dendronotus. The 

 ova are white, without particular arrangement, and almost filling the gelatinous envelope. 



Fig. 8. Back view of Antiopa hyalina. 



9. Under side of the. anterior portion of the same. 



10. A papilla much enlarged. 



11. Dorsal tentacles with crest. 



12. A portion of the spawn. 



