1S4 I •Inly, 



latter, but not joining. The end of abdomen is conieal ; on the under-side (in the 

 (?) are two rounded lobes ; the appendages long and slender, their apices upturned ; 

 about a third from the base is a marking simulating a suture ; the base of appendages 

 and contiguous parts of the abdomen densely covered with fine points, which are 

 also present on the distal parts of the appendages in limited numbers. 



The cases are curved tubes, compactly built of stony fragments 

 and sand grains, and, considering the materials used, are rather smooth 

 externally. In young examples they are conical ; older cases taper 

 very slightly and are truncate at the posterior end, which, in all those 

 before me, is closed with a flat stone, at the sides of which are left 

 small apertures. The cases much resemble those of Sericostoma perso- 

 natum, but may be easily distinguished therefrom by their being less 

 smooth, and by the manner of closing the end of the case, which, in 

 S. personatum, is effected by a membrane with a round hole in the 

 centre. The nymph cases ai-e fixed in various ways to stones, the an- 

 terior end being usually closed by a single large irregularly shaped 

 stone. The cases before me measure from 13 to 17 mm. in length, 

 and the diameter in the largest reached the maximum of about 3| mm. 

 and the minimum of about 3 mm. 



Pictet gives an excellent figure of the larva on pi. xii, fig. 2, 

 "B-echerches" {Mystacides cylindrica) ; the perfect insect, his fig. 1 (Jf. 

 albicornis) is almost certainly the ? of the species under review, but 

 I have never seen a larva at all reBembling that which stands beside it. 



EXPLANATION OF FIGUEES. 



LARVA. 



1. Mandible, left from above (Zeiss A^, e. p. 2). 



2. do. right do ( do. do. ). 



3. do. left from beneath ( do. do. ) . 



4. do. right do. ( do. do. ). 



5. Maxillfc and labium from beneath.. (Zeiss A, e. p. 1). 



6. Labrum from above ( do. do. ). 



7. Antemiro (Zeiss C, e. p. 2). 



NYMPH. 



8. Labrum (Zeiss A, e. p. 1). 



9. Mandible ( do. do. ). 



10. Apex of abdomen from above ( do. do. ). 



11. Apex of appendage more enlarged. 



The note in brackets following the explanation of each figure indicates the objective 

 and eye-piece used in making the relative drawing. 



Carluke, N.B. : April, 1890. 



