14 Mindeskrift for J. Steenstrup. XVI. 



very small cylindrical prominence. In all the specimens seen the body inside the 

 cuticle had contracted and left a space in which always some characteristic small, 

 drop-like, deeply stained bodies were found; in moulting they are left in the cast 

 cuticle. 



The next stage c)isa second Metanauplius, ca. 0,23 — 0,24 mm in length (Fig. 

 16 — 17); the appendages of the former stage are preserved, and in addition maxillæ (mx), 

 two anterior pairs of swimming feet (p^, Pa) and a rudiment of the posterior (pg) have 

 appeared. The maxillulæ are as in the first Metanauplius, only the "shaft" a little larger 

 and — as seen in sections — provided with extremely feeble muscles. The maxillæ 

 are large, directed backwards, as are the swimming feet. The first and second pair 

 of the latter show distinctly a basal part and two clumsy branches, the outer consider- 

 ably larger than the inner and provided with a few short bristles. The third and 

 fourth pairs are simple conical rudiments. The swimming feet are set wider apart 

 from each other than the maxillæ, and the thoracic segments, especially the anterior 

 are distinguishable. The central nervous system forms a dark mass easily seen in 

 profile against the transparent back; in sections the composing ganglionic elements are 

 quite distinct. Muscles to the fully developed appendages as well as rudiments of 

 the longitudinal body-muscles and of those of the developing limbs are observable. 

 The body is somewhat pear-shaped, the back arched, the ventral side more flat but 

 with a prominent mouthpart, now carrying an opening. In sections the rudiment of 

 an oesophagus is seen, passing between the brain and the foremost ventral ganglia 

 and abutting on the embryonic entoderm, not yet forming a hollow stomach. An 

 antennal gland is distinct, also a shell-gland (maxillary-gland). Thus, both these 

 glands here are found together, while generally in Copepoda the antennal gland is 

 said to occur in the larva, and the shell-gland to appear later. 



The next moulting produces d) a third Metanauplius (Fig. 18 — 19). The size has 

 not altered much, the length being ca. 0,248 — 0,280 mm, and the shape of the body 

 is almost the same, only the mouth is less prominent, and the segmentation more 

 distinctly marked, corresponding to the greater development of the thoracic limbs. 

 Most interesting are the appendages, The outer ramus of the antennæ (ag) at first 

 sight seems lost; closer examination shows, that on its place is an empty cuticular 

 case, without any setæ, while the inner ramus has the same shape as in former stages. 

 The mandibles (md) are still more reduced: both rami and almost the whole shaft 

 form empty and naked sheaths, only at the very base of the shaft enclosing a minute 

 papilla of tissue. The maxillulæ — from the first appearance rather rudimentary — 

 are now completely lost. The maxillæ (mx), on the other hånd, are further developed, 

 large and removed from the swimming feet, and directed forwards; they have now 

 distinctly three segments, the terminal one rounded and carrying a hooked spine. 



