64 



CRUSTACEA COPEPODA 



are three' genera, Monstrilla, Haemocera, and Thaumcdeus. The 

 best known type is Haemocera danae (often described as Monstrilla 

 danae). In the adult state (Fig. 30) there are no month-parts ; the 

 mouth is exceedingly small and leads into a very small stomach, 

 which ends blindly, while the whole body contains reserve food- 

 material in the form of brown oil-drops. The sole appendages on 



the head are the first an- 

 tennae ; but on the thorax 

 biramous feet are present by 

 means of which the animal 

 can swim with great rapidity. 

 This anomalous organisation 

 receives an explanation from 

 the remarkable development 

 through which the larva 

 passes. The larva is liberated 



Ant.1. 



Ant.2^' 



Fig. 30. — Haemocera danae, x 40. A, Side Fig. 31. — Free-swimmiug Naupliu.s 



view $ ; B, ventral view i . Ant.l, 1st an- 

 tenna; e, eye ; o^', ovary ; ovd, oviduct ; >S^ 

 stomach ; Th.l, 1st tlioracic appendage ; 

 Th.5, 6th thoracic segment ; vd, vas deferens. 

 (After Malaquin.) 



larva of Haemocera danae ; Ant.l, 

 Ant,3, 1st and 2nd antennae ; e, 

 remains of eye ; 3fd, mandible. 

 (After Malaquin.) 



from the parent as a Nauplius with the structure shown in 

 Fig. 31 ; it does not possess an alimentary canal. It makes 

 it.s way to a specimen of the Serpulid worm, Salmacina dysteri, 

 into the epidermis of whicli it penetrates by movements of the 

 antennae, hanging on all the time by means of the hooks on 

 the mandibles. From the epidermis it passes through the 

 muscles into the coelom of the worm, and thence into the 

 blood-vessels, usually coming to rest in the ventral blood- 



