1752 THE VOYAGE OF H.M.S. CHALLENGER. 



long divergent styles arise from each tergal tube. The hindermost of these is the longest, three 

 times as long as the diameter of the fork-thicket. All anchor-pencils have nearly equal size. 



Dimensions. — Diameter of the whole body 22, of the fork-thicket 5'2. 



Habitat. — South Pacific, Station 166 (west of New Zealand), depth 275 fathoms. 



4. Ccelothamnus maximus, n. sp. 



Sixteen styles straight, of difierent sizes. The four frontal main tubes are already forked at 

 the base, so that from each frontal corner of the two galeae two divergent tubes, an anterior or 

 pectoral and a posterior or tergal, arise. Each of these is again forked, and each branch prolonged 

 into a very long verticUlate style. The hindermost style of each side is the longest, twice as long 

 as the foremost, and one and a half times as long as the two intermediate styles. The size of the 

 anchor-pencUs decreases in the distal third of the styles. 



Dimensions. — Diameter of the whole body 32, of the fork-thicket 7'5. 



Habitat. — Central Pacific, Station 271, depth 2425 fathoms. 



Subfamily 2. Coeloplegmida, Haeckel. 



Definition. — Coelograpliida with an odd sagittal frenulum on eacli galea, and 

 with an external bivalved lattice-mantle, produced by the anastomosing branches of the 

 hollow radial tubes. Si^x to sixteen long styles are prominent over the surface of the 

 mantle, and bear terminal coronets. 



Genus 734. Coelogrcvphis,^ n. gen. 



Definition. — C celographida with an odd sagittal frenulum on each galea and 

 an outer lattice-mantle, armed with six styles (one odd and two paired styles on each 

 valve). 



The genus delographis is the simjilest form of the Coeloplegmida, or of those 

 Coelographida in which the branches of the arborescent tubes are united on the surface 

 of the calymma, and form a delicate bivalved lattice-mantle. In all these Coeloplegmida 

 an odd nasal main style is develoi^ed on the apex of the galea, and this is connected by 

 an odd sagittal frenulum with the mouth of the rhinocanna. Coelographis differs from 

 the other Coelographida in the minimum number of coronal styles, viz., three on each 

 valve, an odd anterior (nasal) and two paired posterior (tergal). 



1. Ccelogr aphis regina, n. sp. (PI. 126, figs. l«-lc/). 



Shell-mantle twice as long as broad, its frontal perimeter isosceles triangular, with a triangular 

 excision at the base, its sagittal perimeter slenderly ovate. Nasal odd style twice as long as the 



1 Gcelofjrci'phis = Hollow style ; xoiXo;, yi^itipis. 



