50 THE VOYAGE OF H.M.S. CHALLENGER. 



Specimens of the Asexual Generation. 



Specimens of Blastozooids, or the " nurse-form " of Doliolv.m, were obtained at the 

 following localities : — 



(1.) April 2, 1874; Station 162, off East Moncceur Island, Bass Strait; surface; 

 surf. temp. 63° "2 ; twenty sjjecimens, varying in size from 5 mm. to 1"5 cm. in length 

 and from 1 mm. to 4 mm. in breadth. The average breadth is 2 mm. 



(2.) October 21, 1875 ; Station 288, South Pacific; lat 40° 3' 0" S., long. 132° 58' 

 0" W. ; surface ; surf. temp. 54°'5 ; two specimens. 



(3.) February 11, 1876; Station 318, South Atlantic; lat. 42° 32' 0" S., long. 56° 

 29' 0" W. ; tow-net at trawl down to a depth of 2040 fathoms; bottom temp. 33° '7; 

 thirty specimens. 



(4.) Same ^ilace and date ; tow-net at surface ; surf. temp. 57°'5 ; five specimens. 



(5.) Ajaril 11, 1876; Station 350, North Atlantic; surface; lat. 7° 33' 0" X., long. 

 15° 16' 0" W. ; surf temp. 84°; one specimen. 



(6.) April 13, 1876; Station 352, North Atlantic; surfiice ; lat. 10° 55' 0" N., long. 

 17° 46' 0" W. ; surf temp. 77° '7 ; one large and one small specimen (mounted as micro- 

 scopic objects). 



(7.) May 3, 1876; Station 353, North Atlantic; lat. 26° 21' 0" N., long. 33° 37' 

 0" W. ; surf. temp. 70°7 ; one specimen. 



(8.) May 7, 1876 ; North Atlantic ; lat. 34° 22' 0" N., long. 34° 23' O" W. ; surface, 

 at night ; surf. temp. 67°'5 ; six large specimens {in bad condition). 



These Blastozooids are large, and have long narrow bodies proA'ided with nine wide 

 muscle bands (see PI. III. fig. 9) and a dorsal outgrowth, which in some specimens is 

 very large. 



The nerve ganglion is placed between the fourth and the fifth muscle bauds. The 

 first and ninth bands are much narrower than the rest, and are evidently the sphincter 

 muscles of the branchial and atrial apertures. The seventh and eighth muscle bands are 

 interrupted in the mid-dorsal line, and their free ends are diverted posteriorly to enter 

 the dorsal outgrowth which springs at that point from the body wall (PI. III. fig. 9, s.). 

 The muscle bands of these specimens are very much wider than those of the Blastozooid 

 of Doliolum mUllcri as figured bj- Keferstein and Ehlers,^ and I am unable to refer them 

 to any known species. Possiblj^ they belong to one of the new species of which the 

 sexual forms have been described al)ovc ; or they may not all belong to the same sexual 

 form. It is impossible to refer them to their species until the life-histories have been 

 worked out on living material. 



1 Zoologische Beitrage, PI. 10, fig. 1. 



