372 Zoological Collections. Inveitebrata. 



original parallel position, and coiled itself in the bottom. On entering the 

 house, I set the one in the glass on the chimney-piece ; and, as the other 

 was more lively, I passed a minute or two in examining it with a pocket 

 lens. I then turned to the Cerwra from which I had the electrical shocks ; 

 and as it had remained coiled together when I set it down, I was surprised 

 to see the glass empty, and the insect gone : it had fallen upon the carpet ; 

 and I was sorely disappointed to find that the child had crushed it with her 

 foot, displacing the intestines, and along with them a clear gelatinous 

 matter, consisting of a great number of short cylinders. Upon attempting 

 to lift one of these with the point of a pin, I found that I pulled more after 

 it. They were attached to each other by small ligaments ; and I was 

 agreeably astonished to discover that they separated from the mass exactly 

 after the manner that the links of a land-measurer's chain are extended, and 

 had been so arranged in the body of the caterpillar, forming an organ, com- 

 posed of these cylinders, at right angles with its length. I convinced myself 

 that this apparatus had nothing to do with the viscera of the insect, and 

 remain satisfied (not altogether philosophically, I must acknowledge) that 

 they composed the electrical organ by which I received the shocks. — 

 W. L. in Loudon's Mag. of Nat. May, 1831. 



Observations on the Belemnites. By M. L. Voltz : — An extended memoir 

 on the Belemnites has recently been published by M. Voltz, which forms 

 an important addition to the works of Schlotheim, Miller, De Blainville, and 

 Raspail. The author gives the following summary of his observations : — 



Of the Alveolus The alveolus is a thin, laminar shell, of a conical form, 



open at the base, having its striae of growth on the outer surface: its, 

 opening is oblique from the belly to the back, where it is terminated by a 

 rounded lobe. This shell is partitioned off into small spaces, by means of 

 very distinct transverse processes, which do not join together as was 

 affirmed by Miller, ( Transact, of the Geological Society of London, second 

 series, vol ii. part i.) These partitions are very luimerous, almost perpen- 

 dicular to the axis of the cone, concave, and smooth, and each provided with 

 a lateral appendage of the form of a hollow tube dilated in the middle : 

 the series of appendages constitutes an articulated siphon, which traverses 

 all the spaces. The siphonic side of the shell is called the venter; the 

 opposite side, the dorsum. 



The striae of growth are of two kinds : on the middle line of the dorsum 

 there is a suite of arches, whose summits are turned towards the opening of 

 the shell ; they are comprised between two straight lines placed symmetri- 

 cally, and extending from the summit of the alveolar cone. I call these 

 straight lines the asymptotes, and the space between them the dorsal region; 

 the latter generally occupies about a fourth of the circumference of the 

 alveolus. On the sides there is another series of striae of growth ascending 

 from the alveolar cone, along the asymptotes, and then bending towards 

 the venter, round which they make a horizontal turn parallel to the suture 

 of the partitions. I call that part of the sides where these striae ascend 

 towards the summit, and turn again to become horizontal, the hyperholar 

 region. The ventral region is the part where they turn round the venter 

 horizontally. 



Of the Sheath. — The alveolus is enclosed in a sheath, which forms the 

 principal mass of the Belemnite, and whose structure is quite different from 

 that of the alveolar cone. It is a conoid or spear-shaped shell, open at the 

 base, and composed of laminae of a transversely fibrous texture covering each 

 other. One layer always projects beyond the preceding, not only at the 

 summit, but also at the base : in this way, the layers form the alveolar 

 cavity, in the interior of which are the striae of growth. The opening is 

 more or less oblique from the venter to the dorsum, which is the converse 



