II FLIES WITH AQUATIC LARV^ 149 



times the egg-mass of a Caddis-fly takes the form of 

 a rope. One such egg-rope (species unknown) I have 

 examined. It was about two inches long, and con- 

 tained very many grass-green eggs, which hatched 

 out and yielded Caddis-worms. 



The marine worm, Sagitta, also lays eggs imbedded 

 in jelly. 



Some aquatic Snails make use in a variety of ways 

 of the same contrivance. The Pond-snails (Limnaia, 

 Physa) lay their eggs in strips of jelly, which are 

 attached to water-plants or submerged stones. 

 Bythinia lays its eggs in three long rows on stones or 

 water-plants (Jeffreys). In Planorbis the egg-mass 

 takes a globular shape (Jeffreys). In Valvata the 

 globular gelatinous mass is invested by a capsule, and 

 attached by a short stalk (Jeffreys). Natica lays its 

 eggs in broad strips of jelly upon shells or stones. 

 The Sea-snail, known to zoologists as Philine or 

 Bullaea, lays its eggs on mud-banks in the form of a 

 small oval mass about as big as a hazel-nut. Upon 

 the surface of this the eggs are disposed in intricate 

 lines. There is a suspensory cord too, which super- 

 ficially resembles that of the Chironomus egg-rope, 

 and points to the necessity of mooring the eggs. 

 Many Nudibranch Mollusca employ a transparent, 

 gelatinous envelope for the protection of their eggs. 

 The eggs of Pteropods are found floating at the sur- 

 face of the sea, imbedded in a gelatinous substance, 

 and forming long, cylindrical strings. Many Cepha- 

 lopods lay their eggs in branched, gelatinous masses 

 attached to fixed objects. 



Fishes furnish several examples of the same thing. 



