I included several specimens in this series of photos to show some variations in the cases. Rather than do each specimen individually and direct viewers to other photos I opted for this.
Cases may or may not have ballast stones attached, more than half of the ones I collected do have ballast stones. The stones can be on the top or bottom of the case and are attached with silk. The larvae were found in an area of moderate current on algae (Cladophora sp.) attached to cobbles. I can't find any reference to this genus using ballast stones. Does anyone know anything about this? The larvae pictured were 3 - 3.5 mm long, the cases were 3 - 4 mm in length and the ballast stones were 2 - 3 mm across. I also found some pupal cases approximately 4 mm in length attached directly to cobbles and attached at each end with silk. None of the pupal cases had ballast stones attached.