w 



<&. 



39 



tends downward and forms the cutting edge" in the Eolis. The posterior and lower half of 

 the cavity enclosed by the jaw (in the Eolis according to Alder & Hancock, tab. 7. fig. 6 

 more than two thirds) is filled up by the tonyuc (Fig. 4. a. fig. 7. & 8), which is a fleshy 

 mass of nearly triangular or wedge-like form, being wide behind, and in front gradually nar- 

 rower or compressed from the sides; so that it is here nearly double as high as wide, with 

 obtusely rounded anterior extremity. Along the middle of the tongue there extends the 

 narrow ribbon-like ravp-plate, (radula) consisting of about 20 transverse rows of teeth, which 

 lie hid in the so-called sheath of the tongue. It takes its beginning above, near to the an- 

 terior end of the tongue, where the largest teeth are found, and extends thence downward 

 along the same and on the ventral side \ its teeth becoming gradually smaller, and backward 

 to more than half the length of the tongue, where it goes over into the sheath of the tongue. 

 There are (see fig. 9.) in each transversal row 3 teeth, of which the middle one is thick strong 

 and broad not curved, but only a little hollowed at the base and conical, bent backward, 

 with obtuse rounded extremity (see fig. 10. & 11) and of vitreous transparent extremely faint 

 light yellowish color; at a short distance from, and in a straight line with this, stand (see 

 fig. 9) 2 others, one on each side, nearly equally long but much thinner, straight triangular, 

 pointed glassy and colorless. As well the middle, as the side teeth are smooth; only at the 

 base of the former there may be observed on each side (fig. 11) a very small roundish node. 

 In front of the tongue there is the secondary bucal cavity (fig. 4. b.) called ,,Bimundhule" by 

 R. Bergh, which according to him is peculiar to the Eolides. The rasp-plate in the Gonieolis, 

 corresponds by its narrowness- with the usual form in the Eolidinse, which family is by Alder 

 & Hancock characterised by ,,a narrow tongue, usually only with a central plate". However 

 it does not quite agree with any of the delineations of these authors. By the presence of 

 side teeth, and by their form, it resembles the Eolis pellucida (Alder & Hancock Tab. 47. 

 fig. 12) the central tooth of which yet differs by being denticulated on the edge; with respect 

 to the smooth central tooth it resembles the Eolis alba (ibid. Tab. 47. fig. 14) which species 

 has however no side teeth. 



The color of the animal is every where yellowish white, with yellow brown liver shi- 

 ning through the skin along both sides of the back, and a more deeply lying oblong light 

 minium red intestine .(probably the ovary) which is especially visible from the ventral side. 



Of this remarkable nudibranch 2 specimens were taken in the summer of 1859 at 

 Christiansund in 5070 fathoms depth. A third specimen was found in the summer of 1869, 

 in the Hardangerfjord at Mosterhavn at the depth of 100 fathoms. 



The present genus may be characterised in the following manner: 



Gen. Gonieolis. M. Sars. 



Corpus oblongum, quadrilaterum, subpalliatum, pallio pede angustiore absque spiculis. 

 Caput latiusculum, tentaculis 4 simplicibus, conico-acuminatis, non retractilibus, quorum 2 



The figure 7 is represented in an inverted position. / 



