DORIDIDA. 369 
The only Nudibranch with a solid upper jaw, is Agirus 
punctilucens. In other instances the two halves are articulated 
and act aslateral jaws. In Aigirus the mouth is also furnished 
with membranous fringes. Ancula cristata has a formidable 
spinous collar. The skin acts as an accessory breathing-organ ; 
it performs the function entirely inthe Elysiadz, and in the other 
families, when by accident the branchiz are destroyed. ‘The 
water on the gills is renewed by ciliary action. The fry is pro- 
vided with a transparent, nautiloid shell, closed by an oper- 
culum, and swims with a lobed head-veil fringed with cilia, like 
the young of most other gastropods. 
“While the numerous tribes of Mollusks furnished with testa- 
ceous coverings offer us objects of contemplation remarkable 
alike for their extreme beauty and the durability of their calea- 
reous envelopes, the scarcely less extensive and certainly far 
less known families of naked-gilled gastropods exhibit an aston- 
ishing variety of form, extreme delicacy of organization, and 
great diversity of color to captivate the eye and occupy the 
attention of those who wander by the shore or explore the 
depths of the ocean. Clinging to the stems of floating sea- 
weeds, many, like the Anthobranchs, will be seen extruding 
their flower-like gills of surpassing elegance, exploring with their 
foliated tentacles or complex mantle-filaments the plants around 
them, the brilliant hues of their striped or spotted bodies 
glancing through the water; some will be observed with bodies 
so fragile and pellucid that you may see the color of their blood 
and count the pulsations of their hearts; some will be seen to 
have their gills disposed in rows of papillary tubercles on the 
sides of their bodies, like the Aolids, or tree-like and branching, 
like the Tritonias; the foreheads of some will be smooth and 
simple, while those of others will be found adorned with various 
singular appendages ; in others, again, all processes will disap- 
pear, all branchial arrangements vanish, and we shall meet with 
forms almost as simple in their appearance as the Nemertoid 
types among the Annelids.”—H. and A. ADAms. 
SuBporDER ANTHOBRANCHIATA. 
The branchiz more or less surrounding the anus upon the 
medio-dorsal line. 
Famiry DORIDIDA.- 
Mantle (nothwum) large, without marginal appendages; skin | 
generally very spiculose ; dorsal tentacles (rhinophora. ) laminate 
and retractile within ‘cavities. ~Dentition (siti, 69). 
Doris, Linn: 
Biyh: livia Bohadseh. Arehidoris, Bergh. 
Distr.—107 sp. Universal.” D. Johnstoni; ‘Alder and. Haircuck 
(xc, 92). 
