18 
THE YOYAGE OF H.M.S. CHALLENGEE. 
SURVEY OF THE GENERA AND SPECIES, HITHERTO KNOWN, REFERRED 
TO THE APNEUMONA. 
Family I. Synaptida;. 
Tentacles digitate or pinnate. Body cylindrical. Deposits in the shape of anchors 
or wheels, seldom absent. 
Genus 1. Rhabdomolgus, Keferstein, 1868. 
Tentacles ten, elongate, undivided, slightly lobate on the sides. Deposits absent in 
the perisoma (?). Hermaphrodite (?). 
Rhabdomolgus ruber, Keferstein, 1863. 
Habitat. — St. Vaast (Keferstein). 
This remarkable form is very doubtful, and needs to be re-examined. 
Genus 2. Anapta, Semper, 1868. 
Tentacles twelve, small, pinnate, each with eleven fine digits. Body covered with 
papillae, devoid of other deposits than minute elongate or oval grains. Her- 
maphrodite. 
Anapta gracilis, Semper, 1868. 
Habitat . — Manila (Semper). 
Genus 3. Synapta, Eschscholtz, 1829. 
Tentacles ten to twenty-five, digitate or pinnate. Deposits — anchors, anchor-plates, 
and miliary granules. Hermaphrodite. 
A. Tentacles pinnate, mostly with numerous, always with more than five digits. Anchor- 
plates roundish or oval, always (excepting in Synapta heselii) symmetrically formed with 
six to seven large dentate holes, and, besides, some emaller smooth ones at their narrower 
articular end, which forms a distinct bow. Circumference of the plates mostly smooth 
and complete. 
