NOTES AND MEMORANDA. 409 



only knew of four of these cases. I have already found nine, which 

 must be classed under six quite distinct genera : — 



I. Cases resembling mussel-shells, with narrow slit-like anterior 

 and posterior apertures (as Hydroptila). They are carried on the 

 sharp edge. (They look particularly like mussels when they are 

 formed of rod-shaped diatoms, which then represent as it were the lines 

 of growth.) 



1 . Upper and under edges parallel, almost straight ; coated out- 

 side with fine sand. Larvse with three caudal tracheal gills. 



2. Of a similar shape but made of algfe or diatoms. Larvas 

 without gills. 



3. The dorsal angle strongly arched ; the case made without the 

 aid of foreign materials. 



II. Case formed of diatoms, the sides pressed together, with a 

 narrow anterior and posterior slit ; the edge of the back has two funnels 

 (I call them for the present Dicaminus). For entering the pupa stage 

 they are fixed upright, and sometimes whole villages of these cases are 

 found attached to stones. The use of the funnels is evident, viz. to 

 give free entrance to the water necessary for respiration. The larvas 

 in the small mussel-like cases which have no such tubes, are seen to 

 make, almost continuously, brisk serpentine movements in their cases 

 with the posterior j^art of their body — with the result of introducing 

 fresh water. The Dicaminus larva never does this. 



III. Almost cylindrical, coated externally witli fine sand. Diminu- 

 tive tubes, only 2 mm. long and about • 5 mm. in diameter. 



IV. Cases attached to movable stalks. 



V. Scutiform cases, fastened all round, similar to an egg-case of 

 Nephelis, with a small hole at each end. 



VI. Flask-shaped cases (Lagenopsyche nov. gen.). These are 

 especially remarkable. In distinction to almost all the known cases 

 of Hi/droptilidce, the anterior and posterior ends of which are equally 

 and uniformly made use of for the larvte to creep both in and out of, 

 the cases of the Lagenopsyche difter greatly at the two ends, the 

 anterior opening being round, and the posterior a long narrow slit. 

 All the other Phryganeidce. look out of the last formed and wide part 

 of their tubes ; LagenopsycJie out of the first formed neck of the flask. 

 I know no other instance of the change in position of the pupa in its 

 case (what for it is front, above, and below, for the larva was behind, 

 right, and left). The imago usually creeps out in the first hour or 

 two of the afternoon." 



Development of the Silkworm.— A preliminary account of his 

 researches on this subject is published, by A. Tichomirofi",* whose 

 chief results are as follows : — 



1. The author was able to confirm Bobretsky's observation as to 

 the passage of amoeboid cells from the interior to the periphery of 

 the egg, in order to form the blastoderm. This process was best seen 

 on the second day after the eggs were laid. There was no evidence 

 to show whether these amoeboid cells originated, according to Bobret- 



* 'Zool. Anzeiger,' ii. (1879) 64. 



