July 1, 1868.] 



IIARDWICKE'S SCIENCE. GOSSIP. 



153 



the whole together heterogeneously, without the 

 slightest semblance of order. A conchologist might 

 frequently examine these cases with profit, for a 

 good miscellaneous shell-case will give a better idea 

 of what fresh-water 3/ollusca may inhabit any par- 

 ticular spot than probably would hours of dredging 

 and searching. It matters little whether the 

 shells be empty, or still contain their proper 

 inmates ; these latter must submit to be dragged 

 about at the will of the creature that lias thus 

 unceremoniously pressed them into its service ; and 

 if they do not die in that position, they must 

 patiently await the time when, after the escape of 

 the perfect insect, the binding materials of the case 

 may rot, and set free the various matters composing 

 it. The cases of smaller species of the same family 

 are also frequently appropriated (figs. 140 to 151). 

 Several cases, all of which probably pertain to this 

 species, are here figured from specimens in my col- 

 lection. Another common form of case is that made 



Fig. 152. Case of Limnephilus lunatus. 



byZ. lunatics (fig. 152) and Anubolia nervosa (fig. 153). 

 This consists of a tube made of sand or shell frag- 

 ments, to the outside of which are attached long 



Fig. 153. Case of Anaholia nercosu. 



twigs, husks, or pieces of wood, as balancers; the 

 twigs often extending far beyond one end of the tube. 

 One colony of L. lunatus, dwelling in a dike under a 

 beech-tree, had appropriated the empty and open 

 husks of the beech-mast, and it was ludicrous to see 

 these latter moving about at the bottom by an 

 agency that was not at first very apparent. 



A not very abundant case, sometimes to be found 

 in ponds, is formed of entire leaves or large pieces, 

 usually of sallow or poplar, also sometimes of 

 pieces cut out from the stems of bulrushes, &c, 

 and laid more or less flat over each other, forming 

 broad flattened masses, in the interior of which 

 is the slender tube containing the larva : this is the 

 work of Limnephilus pellucidus (fig. 154) . 



Straight or curved tubes, uniform, or gradually 

 tapering at one end, and formed of sand or very 

 small stones neatly cemented together, are very 

 common, and some of them are very elegant objects: 

 they are formed by various species of Limnephilus, 

 Stenophylax, Sericostoma, Leptocerus, Setodes, &c.&c; 



but space forbids me to enter more fully into their 

 peculiarities. Some species of Setorles make delicate 

 little tubes, entirely formed of silky secretion, 

 without any mixture of extraneous matters. Occa- 

 sionally one may find short quadrangular cases, 



Fig. 154. Case of 

 Limnephilus pellucidus. 



Fig. 155. 

 Case of Stenophylax, 



formed of vegetable matters, the angles being well 

 marked. It is not yet certain what species manu- 

 facture these. 



Fig. 156. 

 Case of Sericostoma. 



Fig. 157. 

 Case of Setodes. 



Fig. 153. Quadrangular Cases. 



The most extraordinary of all British cases is that 

 formed by Molanna angustata (fig. 159), which is 

 not uncommon in ponds, especially those with a 

 sandy bottom. It is long, broad, and flattened, and 



Fig. 159. Cases of Molanna angustata. 



formed entirely of fine sand ; the upper surface, at 

 the anterior end, projects considerably beyond the 

 lower ; thus forming a cover, protecting the larva 

 when it protrudes its head and anterior segments 

 in search of food. An allied case is found in 

 Ceylon ; only in this the case proper is a slender 

 tube, to the upper end of which is attached a 

 broad semicircular shield, convex above and con- 

 cave beneath, answering the same protective pur- 

 poses (fig. 160). 

 The minute insects of the genus Ilydroptila, so 



