CEPHALOPODA (dIBRANCH IATA) . 
Moll 39 
some other lower Glastropods, the genital glands being situated freely in 
the abdominal cavity and not continuous with the oviduct or vas 
deferens. The ventral pair of gills in Nautilus is homologous to the only 
pair of the Dihranchiata, no trace of a rudimentry second pair is to be 
found in the latter, and, therefore, the Tetrabranchiata are to be derived 
from the Dihranchiata, contrary to the common opinion. The author 
thinks that the distinction of GEgopsidoi and Myopsidoi is rather artificial, 
Loligo being in many points more nearly allied to Ommastrephes than to 
Sepia, and that the Octopodidm are a rather primary form of Cephalopods. 
Z. wiss. Zool. XXXV. pp. 1-22 ; abstract in J. E,. Micr. Soc. (2) i. p. 23. 
J. Brock expatiates further on the phytogeny of the Cephalopods, 
comparing chiefly the structure of the genital and circulatory organs, 
absence or presence of the milt, the muscular system, and the cartilages 
of the mantle and the radula in the genera Ommastrephes, Enoploteuthis, 
Chiroteuthis, Loligopsis, Owenia, Onychoteuthis, Sepioteuthis, Octopus, 
Eledone, and Argonauta, for which he gives 4 comparative tables ; he 
comes to the same conclusions as those mentioned in Zool. Rec. xvi. Moll. 
p. 37, viz., that Nautilus is a very primitive form, rather near the com- 
mon root of the Tetrabranchiata and Dibranchiata and that the latter are 
to be divided into three anatomically well defined “ phyla ” : — (Egopsides, 
which are the oldest. My apsides, and Octopodidcc, the last are the most differ- 
entiated, and must have branched off from the common stem at an early 
period, a long time before the tertiary epoch ; Loligopsis and Veranya 
are those (Egopsides which present a clear approach to the Octopodidm. 
Within all three “ phyla ” there is a parallel development in the reduc- 
tion of the shell, Cirroteuthis with internal shell being the most primitive 
form of the recent Octopodidm, and Ommastrephes exhibiting the phragmo- 
cone of the Belemnites at the extremity of its internal shell ; in the same 
manner all three “ phyla ” have a tendency to lose the cartilaginous sup- 
porting apparel of the mantle and to acquire instead of it a muscular 
connection between neck and mantle, which is most perfectly attained in 
the Octopodidm, but only imperfectly in the (Egopsides by Loligopsis. 
Morph. JB. vi. 112 pp. pis. xi. & xii. ; abstract in JR. Micr. Soc. iii. 
pp. 601-604. 
DIBRANGHIATA. 
OCTOPODA. 
Octopus obesus and lentus, spp. nn., Verrill, Am. J. Sci. (3) xix. pp. 137 
138, & 294, near Nova Scotia. 0. piscatorum (Verrill), description copied 
in Ann. N. H. (5) v. p. 192. 
Octopus maorum, sp. n., Hutton, Manual N. Zeal. Moll. p. 1, New Zea- 
land. 
Tremoctopus violaceus (Chiaje) and catenulatus (Fer.), radula : Brock, 
Morph. JB. vi. pi. xii. fig. 10, E. F. 
Ocythoe tuberculata (Rafinesque) = Tremoctopus catenulatus (Yerany) ; 
Steenstrup, Overs. Dan. Selsk. 1880, p. 104. 
