478 Prof. E. W. MacBridc on Ecldnoderm Larccv. 



disk of the future starfish liave iu each case a heart-shaped 

 dorsal process ou the prseoral lobe. 



In the case of two or three of the specimens submitted to 

 my inspection the prgeoral lobe had been so injured that it 

 was not possible to be certain as to its shape ; but, except in 

 one case, the other characteristics left no doubt in my mind 

 that these larvae were also to be regarded as B. asterigera. 

 In the case specially referred to — the only larva recorded in 

 haul 5 (see below) — there was a well-marked five-rayed disk 

 and a very long prseoral lobe ; but the processes were shorter 

 and the whole larva decidedly smaller than the typical full- 

 grown Bipinnaria asterigera. The only other species of 

 Bipinnaria so far known which possesses such a long praeoral 

 lobe is the larva of Luidia ciliata, and this is at once distin- 

 guishable by the fact that the starfish disk which it bears is 

 seven-rayed. On the whole I conclude that this somewhat 

 aberrant' larva is also to be regarded as Bipinnaria asterigera. 

 Dwarf larvse are not of uncommon occurrence in other species 

 of Echinoderms (I have met them in Asterina gibbosa and in 

 Echinus esculent us). 



Subjoined is a list giving the contents of each haul as 

 submitted to me : — 



Haul 1.— Lat. 52° 4'-5 N., long. 12° 27' W. Depth 270 

 fathoms. Net 2 b. 

 One damaged specimen of Bipinnaria asterigera with no 

 trace of the starfish disk. 



Haul 2. — Same place and same depth. Net 2 c. 



Several full-grown specimens of Bipinnaria asterigera with 

 a large disk ; one with rudimentary disk. 



Haul 3. — Same place and same depth. Net 2 e. 



Two young Bipinnaria asterigera ; the starfish disk not 

 yet formed. 

 Haul 4. — Same place. Depth G20 fathoms. Net 2/. 



Several Bipinnaria asterige7'a with far- advanced starfish 

 disk ; one or two younger stages without disk. 



Haul 5.— Lat. 52° 4'-5 N., long. 11° 20'- 1 W. Surface. 

 Net 1 a. 

 One aberrant larva with five-rayed disk (see above). 



Montreal, 

 Jan. 16, 1900. 



