studies on marine Ostiacods 



135 



The following larval stage is very like the preceding one, but the fifth limb is somewhat 

 more diiTerentiated. The sixth limb is distinctly two-jointed; its proximal joint has one bristle, 

 its distal joint none. The furca has the same number of claws as in the preceding stage, but 

 the difference between main claws and secondary claws is less striking. 



The next larval stage is characterized by the fact that the sixth limb has almost a 

 definitive shape, but it has comparatively few bristles; according to pi. 34, fig. 24 the end joint 

 has only five bristles, three anterior ones and two posterior ones; the cleaning limb is developed 

 as a short, unjointed, upward pointing appendage without bristles. The furca has eight claws. 

 With regard to the further development of this form this author writes as 

 follows, p. 185: ,,Ueber die weiteren Entwicklungsstadien kann ich fur Cypridlna mediter- 

 ranea keine Angaben machen. Nach Untersuchungen an Pyrocypris dUrften noch ver- 

 schiedene Hautungen folgen. Die Veranderungen wiirden, abgesehen von einer allgemeinen 

 GroBenzunahme und einer Vermehrung der Borsten an verschiedenen Gliedmaafien, in 

 einer Streckung des PutzfuBes bestehen, verbunden mit dem zuniichst nur andeutungs- 

 weisen Auftreten von Gliedern und dem Erscheinen einzelner Borsten an der Spitze." 

 According to C.Claus, 1865,p. 153,theyoimg- 



est larval stage (which is still in the brood chamber) 



is quite without the two posterior pairs of limbs. 

 It follows from this that the results obtain- 

 ed by these authors agree very well, on the 



whole, with what I observed above for Cypri- 



dina (Doloria) pecdnata. There are, however, 



some small differences to note: thus, for instance, 



in the third larval stage of Cypridina (Vargula) 



mediterranea, which seems to correspond to 



Stage III of Cypridina (Doloria) pectinata, the 



cleaning limb is very short. Stage V and Stage VI 



seem to have been confused by G. W. MLfLLi:i{; 



they seem to correspond to the youngest larval 



stage given by this author. 



Measurements: ^ 



Sixty free-living individuals of Cypridina 



(Doloria) pectinata from the above-mentioned 



station were measured. The results of these 



measurements are given in fig. XX. 



The column 17 — 21 comprises the em- 

 bryos in the brood chamber; when these leave 



the mother they probably have a length of 



about twenty divisions. A mature male measured 



62 divisions. The mature females are represented 



by columns 73 — 76 and 77- 



3 u iff. a. n >■ 



Fig. XX. —Curves showing the results of my meas- 

 urements of the lengths of the shells of a number 

 (^r larvae of Cypridina (Doloria) pectinata from Tierra 



del Fuego. — = females and young larvae: = 



= males. The abscissa represents the lengths of the 



shells e.xpressed in divisions of a micrometer (29—30 



divisions = 1 mm.); theordinate represents the number 



of. specimens measured, 



