86 Thirty-Second Report on the State Museum. 



These cases are of various forms and proportions, sometimes being of an oval 

 shape, and attached by the rim to the under surface of a stone, but more gen- 

 erally of an elongated, cylindrical form. These latter are closed at one end, 

 with the other remaining open to admit of the extrusion of the head and thoracic 

 segments of the larva, for the purpose of locomotion or taking its food. It retains 

 its position within the case by means of some hooks at its posterior extremity, 

 and three mammiform protuberances on its first abdominal segment (shown in 

 fig. 9, plate 5), adhering so strongly that considerable force is required for its 

 dislodgment. 



Sub-fam. Rhyacophilidce. — In fig. 1, plate 5, one of the oviform, attached 

 cases, above referred to, and quite common at Caledonia, is represented. They 

 are usually considerably longer than broad, as I recall them in place — the 

 examples at hand having evidently been distorted in their careless removal from 

 the stone. They belong, as Dr. Hagen informs me, "to the sub-family of 

 Rhyacophilidw. There are only eight North American species described, but 

 a number of others are known. From the small size of the examples sent, they 

 probably do not belong to Rhyacophila proper, but to some other genus yet to 

 be established. The cases of these larvae are composed of pieces of stone, or 

 other rough material, and are attached to the surface of stones. The larva is 

 not confined to its case, but passes in and out of it through an aperture. Most 

 of the species of Rhyacophila build for the nympha, a brown, membranaceous 

 cocoon, which is wanting in these examples." 



Westwood, loc. cit., vol. ii, p. 62, fig. 68.6, represents a case somewhat simi- 

 lar to this, but more elongate, and composed of finer material, which he refers 

 to Hydropsyche senex Pictet. He says of the larvae : " They are compelled to 

 quit their retreat whilst searching for food, in a naked state, and they are accord- 

 ingly better fitted for such a kind of life, by having the abdomen of a firmer 

 consistence. Their pupae are inclosed in a single silky envelop, to which various 

 materials are attached." 



Hydroptilae. — In fig. 4, plate 5, a case of one of the Hydroptilae (natural 

 size\ is shown. Dr. Hagen writes of it : " It is probably of the genus Phrix- 

 ocoma Eaton. Of the Hydroptilae cases very little is known. I have worked 

 much at them, but have not yet published. The shape and manner of living 

 are similar for all, but some cases consist only of silk and fibres of Chara, very 

 neatly arranged. A full account of one is given in the London Quarterly 

 Journal of the Microscopical Society, 1857, New Series, Vol. VII, No. xxv, 

 p. 83 ; and we have found a similar one here." 



Westwood (loc. cit.), fig. 68.5, figures the case of the European Hydroptila 

 pulchricornis Pictet — "a small, flattened, kidney-shaped case, opened by a 

 slit at each end." These cases resemble somewhat the interior cases of Rhya- 

 cophila, but differ from them in their not being inclosed in an additional outer 

 case, and in their swimming freely in the water. 



Sub-fam. Sericostomidce. — The cases constructed by the larvae of this group 

 are represented in fig. 5, plate 5, given in twice the natural size. They are sub- 

 cylindrical, being somewhat flattened, and usually larger at their open end. 

 They are composed of grains of sand, bits of stone, or other hard material, and 

 occasionally a small shell is worked in. Often a larger stone is attached to each 

 side, as shown in the figure, to give them, it is supposed, additional weight. 

 But few of the species have been described. Dr. Hagen refers the species here- 

 with figured to Silo, or some nearly related genus. Quite a number of these 

 cases, when collected, were slightly fastened at one extremity to stones, indi- 

 cating the readiness of the occupants for their pupal change, or in the examples 

 where the cases were closed, their having already entered upon that stage. In 

 their early state, they are numbered among the unattached forms, moving freely 

 in the water. 



