VAIN DER HGEVEIS’S ZOOLOGY. 
91 
With regard to the Cephalopoda, although the translator has recorded 
a good deal of what is known respecting the Hectocotyli, yet we would 
have expected him to have alluded in vol. ii. to the very important me¬ 
moir in the “ Transactions of the Royal Danish Society”, (vol. iv. part i. 
1856), by Steenstrup, entitled, “ The Structure of the Hectocotylus in 
the genera Argonauta and Tremoctopus, illustrated by observations on 
similar structure in the Cephalopoda in general.” This memoir proves 
that the phenomenon is not confined to the two genera named, in which 
it is most fully developed. Steenstrup is of opinion that it has not only 
a physiological value, but also a systematical significance. The follow¬ 
ing Table of the most striking differences in the mode of its determina¬ 
tion will illustrate this :— 
I. Octopods.—These possess in the highest degree the faculty of 
reproducing lost arms, and parts of them. A. Hectocotylus, deciduous, 
colourless, developed in a sac. a. Hectoc, the third arm of the left side =» 
Argonaut a. b. Hectoc, the third arm of the right side = Tremoctopus. 
B. Hectoc, persistent, coloured, free, the third arm of the right side = 
Octopus ; Heledone. II. Decapods.—Destitute of the faculty of repro¬ 
ducing the arms. A. Myopsidae.—The Hectocotylus developed, a. In the 
first arm of the left side; a, only the middle of this arm ; the first of the 
right in some degree similarly affected = Rossia. b. In its whole extent, 
and this arm only = Sepiola. b. In the fourth arm of the left side, a, 
at the base only = Sepia, b, at the tip only = Sepioteuthis ; Loligo. c, 
in its whole extent, Loliolus. B. Oigopsidse (I)' Orb.) Ho Hectocotylus 
arm developed, as far as is known. The genera Ommatostrephes ; Ony- 
CHOTEUTSIS ; LOLIGOPSIS. 
It would appear that Aristotle was familiar with this phenomenon, as 
regards the Octopus vulgaris of the Mediterranean. This leads us to remark 
that our common Loligo is not the L. vulgaris of Lamarck, as stated by 
Forbes and Hanly; neither is it the L. magna of Rondelet, as Leach 
and a few others thought. Steenstrup accordingly has adopted the trivial 
name of Forbesii for the L. vulga/ris of E. Forbes and S. Hanly. On 
leaving the Mollusca, we may state, that our author, not satisfied with 
the order of succession of the families of the Lamellibranchiata, would, 
had he to rewrite his volumes, entirely remodify this order. 
- The second volume begins with the Fishes. Van der Hoeven says, 
very truly, that the arrangement of the fishes is attended with great diffi¬ 
culties, and it seems to be rather the avoidance of what is frail, than the 
attainment of what is perfect, that the most earnest investigations and 
the most learned disquisitions have yet to offer ; and there are very few, 
we hope, presumptuous enough to say ‘Ho’ to this; and there are very few 
who have laboured in this particular department but have speedily found 
out its verity. On the first step of the threshold we meet with an Am- 
phioxus—that most imperfect of all vertebrate animals—and as we 
leave this abode, tenanted by Neptune’s army, we stumble over a Le- 
pidosiren vainly imploring us to bore a hole in his nose, and he would 
crawl away. By-the-by, it is a curious fact, and one we have on fair 
authority, that if into the breathing holes of these creatures (L. annec - 
