970 



INSECTA. 



forms a large bag or crop, which we shall pre- 

 sently see more perfectly developed in the 

 Haustellata. While passing into the abdomen, 

 this part becomes suddenly constricted, and 

 terminates in a short neck, immediately behind 

 which is an oval and very muscular gizzard (i), 

 which is developed internally into four broad 

 longitudinal horny ridges (a, b), armed with 

 strong sharp bristles, as formerly shewn by 

 Leon Dufour* in insects of this family. Be- 

 tween these ridges are two channels armed in 

 like manner with a double row of minute 

 hairs, which assist in more minutely comminu- 

 ting the hard parts that are passed into the 

 gizzard and escape trituration by the ridges. 

 The substance of the gizzard is particularly 

 muscular, and resembles in colour the gizzard of 

 a bird. On its external surface the thin shining 

 peritonceal coat is very distinctly seen. At its 

 base the gizzard is much constricted, and the 

 ridges within it meet together so as to form a 

 distinct valve, by which this is divided from the 

 next portion of the alimentary canal, the chylific 

 venthcule (A;). This part is capacious and 

 muscular, and the double mucous lining within 

 it is very distinct. It is of considerable length, 

 and is gradually decreased in size from its com- 

 mencement to its termination at the pyloric 

 valve, where, as in the larva, it receives the he- 

 patic vessels. It is v covered throughout its 

 whole course by an immense number of appa- 

 rently ccecal vessels (a, 6, c), which in the upper 

 half of its course are of considerable length, 

 but in the lower become gradually more and 

 more shortened. Burmeisterf thinks these 

 coecal vessels are derived entirely from the inner 

 or mucous coat of the ventricule by intussus- 

 cepted portions, which pass through the mus- 

 cular coat between the fibres which are pushed 

 aside by them, and consequently that they do 

 not derive any covering from the muscular coat, 

 but of this we have considerable doubt. In- 

 ternally they certainly open each by a distinct 

 valvular orifice, derived from the mucous lining, 

 as we have seen in Carabus monilis (6), and 

 externally are covered by the peritonceal coat, 

 and on each side are furnished with a minute 

 ramifying tracheal vessel, derived from the tra- 

 cheae which are distributed over the alimentary 

 canal, as shewn by Dufour. We cannot, how- 

 ever, imagine that they derive no covering from 

 the muscular coat of the ventricule, more espe- 

 cially while it is admitted that the coecal appen- 

 dages attached to the anterior and posterior por- 

 tion of the ventricule in the GryllidcE derive a 

 portion of their structure from the muscular 

 coat as well as the mucous. These are most 

 decidedly secretory organs, and elaborate a 

 fluid, probably distinct in its chemical composi- 

 tion from that of the biliary vessels at the 

 pyloric extremity of the stomach. The ilium 

 (/) is of considerable length. On its exterior 

 surface the longitudinal muscular bands are 

 distinctly marked. It is much longer in pro- 

 portion to the other parts of the intestine in the 

 perfect insect than in the larva. It terminates 

 in a very large pear-shaped colon (m, n), the 



upper part of which corresponds to the coscum, 

 which we shall see highly developed in some 

 other species. It is there marked by six elon- 

 gated elevated glandular protuberances, situated 

 between the longitudinal muscular bands. 

 These elevations seen on the exterior of the part 

 correspond to others which we have found 

 equally strongly marked in the colon of Hy- 

 menoptera, and we suspect are the mucous 

 glands of the great intestine. The colon is 

 usually distended with fasces, and terminates in 

 a very short narrow rectum (o). At each side 

 of the colon are situated the anal or urinary 

 vessels (s), which we shall presently describe. 

 This may serve to illustrate the general form of 

 the alimentary canal in carnivorous Coleoptera. 

 In certain parts of its course it is, however, 

 more developed in other species. Thus in the 

 Dyticida:, we have found the oesophagus in 

 Hydaticus cinereus, as described by authors in 

 DyticttSj expanded into a large crop-shaped 

 bag, and the stomach shorter than that of the 

 Carabid& t and covered by Ions; cceca throughout 

 its whole extent. It receives at its base the in- 

 sertion of four large hepatic vessels, and also 

 two very much smaller ones, similar to those 

 just seen in thelarva oftheCalandra. The anal 

 vessels are also present, but their excretory 

 bladder is larger, and its neck much shorter 

 than in the Carabida. The most remarkable 

 structure is in the proventriculus or gizzard. 

 The external appearances of this part resembles 

 that of an acorn in its cup. It is exceedingly 

 muscular, and is armed internally with four re- 

 markable teeth arranged around its inferior por- 

 tion, between four horny ridges developed from 

 the mucous lining of the part, and covered with 

 very strong stiff hairs, as in the Carabida. Each 

 of these teeth is broad and somewhat oval at its 

 base, and in shape resembles a helmet, the crest 

 of which is acute, and armed with two sharp- 

 pointed prominences adapted for cutting the 

 food, which it is known is swallowed more rapa- 

 ciously and less comminuted by these insects 

 than by Carabida. This form of alimentary 

 canal with a gizzard and gastric cceca exists in 

 the Silphida* and most of the carnivorous 

 feeders. Thus it exists also in Staphylinidefi 

 in which we have found the gizzard in Creoplii- 

 lus maxillosus armed with double longitudinal 

 horny ridges, covered with stiff hairs as in Ca- 

 rabus, like which also the stomach is covered 

 with gastric co3ca, which are larger at the an- 

 terior than at the posterior part of the organ. 

 The anal vessels are also largely developed. 

 Dufour has observed the same in Staphyli- 

 nus erythropterus. The gizzard is also found 

 in some of the Neuroptera. It is very largely 

 developed in the carnivorous Panorpa corn- 

 munis, in which, however, we have not found it 

 thrown into regular longitudinal folds, but into 

 transverse and oblique rugae covered with stiff 

 hairs. The alimentary canal in this species is of 

 considerable length, perhaps nearly three times 

 that of the body. The oesophagus is short, 

 but is developed at its under "surface into 

 a minute oval crop, perfectly distinct from 



* Annales des Sciences Naturelles, torn. ii. pi. 20. 

 t Op. cit. p. 132. 



* Dufour, op. cit. torn. iii. pi. 13, fig. 5. 

 t Id. 



