THE FORM OF THE LARVA. 



149 



carefully examined by Dohrn, has a compact body (Fig. G9), some- 

 times almost square, or else rounded, seldom long or oval. The 

 body is not externally segmented, although it carries three pairs of 

 limbs ; in this respect this larva bears a certain resemblance to the 

 Crustacean Nauplius. It has been compared with the latter, but 

 the resemblance is merely superficial. 



Fig. 69. — Larva of Achclia lacvis immediately after hatching (after Dohrn). 7-777, limbs; bg, 

 strands of connective tissue ; d\ spine on limb 7 with gland (dr) ; da, enteron ; /, filament 

 of the glandular secretion ; g, brain (with the eyes above it) ; m, muscles ; s, proboscis ; 

 v, vacuoles in the gland. 



The larva, as already stated, is supplied with three pairs of 

 limbs. The most anterior limb has three joints, and is chelate. 

 At its base it has a movable spine (Fig. 69, d), which, in other 

 genera, is considerably longer than in the larva of Achelia depicted 

 in Fig. 69. This appendage brings about a certain similarity 

 to the biramose limbs of the Crustacea, but we would not lay 



