THE DEVELOPMENTAL STAGES OF LABIDOCERA

¹ From the Scripps Institution of Oceanography of the University of California, La Jolla, California

1. The developmental stages of Labidocera trispinosa and L. jollæ are described and figures given.

2. Each species passes through the typical six nauplius and six copepodid stages.

3. It is probable that in the first nauplius stage the species are indistinguishable.

4. In the adult condition the species are sharply distinguished, but during the second to sixth nauplius stages and during the first copepodid stage they are separable only by small but yet definite specific characters, the most useful of these being the type of masticatory hook occurring on the second basipod of the second antenna.

5. Specific identification of the nauplius larvæ was established by experimentally rearing the sixth nauplius stage through metamorphosis.

6. Tables I and II are given to facilitate identification of the nauplius and copepodid stages.

7. The nauplius larvæ of Labidocera are very similar to the larvæ of Epilabidocera and are believed to typify the nauplius larvæ of at least other nearly related genera of Pontellidæ.