136 CLARKE ON HYDROIDS 



Calyptospadix gen. nov. 1 



Trophosome. Hydrophyton consisting of a branching hydrocaulus rooted by a creeping, 

 filiform hydrorhiza. Hydranths fusiform with filiform tentacles which are arranged in a 

 single verticil round the base of a conical hypostome. Perisarc developed into large 

 hydrotheca-like processes. 



Gonosome. Sporosacs developed on the ultimate "ramuli beneath the terminal hy- 

 dranths. 



Calyptospadix cerulea nov. sp. Plate 7, figs. 1 to 9. 



Trophosome. Hydrocaulus simple, not much branched, of equal size throughout and 

 attaining a height of three to four inches ; branches irregularly arranged upon all sides of 

 the stem; those of the proximal third of the hydrocaulus are very short, while those of 

 the remaining portions are the longest in the colony, some of them being half the length 

 of the main stem ; branchlets arranged alternately ; hydranths fusiform with a conical pro- 

 boscis and eight to ten, occasionally twelve, tentacles, the latter arranged in a single verti- 

 cil, protected by cup-shaped processes of the perisarc, roughened exteriorly by circular 

 ridges and which very nearly cover the entire hydranth when it is fully retracted ; perisarc 

 annulated at the bases of the branches and branchlets. Gonosome. Sporosacs developed in 

 clusters of from three to five on the ultimate ramuli just beneath the hydrotheca-like 

 expansions ; a large number of planulae developed in each female sporosac, the spadix 

 unusually large. 



Color. The female gonophores, the ova, and the planulae in their earlier stages, bright 

 blue. 



Development of gonosome. July and August. 



Bathymetrical distribution. Littoral and coralline zones. 



Habitat. Spiles of wharf and old shells. 



Locality. Fort Wool, Virginia. 



It is very intex^esting to notice the approximation to the calyptoblastic forms indicated 

 in this species, shown by the hydrothecae, which are of fully as much protection to the 

 hydranths as are the slightly developed hydrothecae of many species of Halecium. The 

 reproductive zooids have a perfect chitinous covering, but it is developed around a sporosac 

 and so is not a gonangium according to Allman. This author states that a gonangium is 

 developed about a blastostyle. His definition of the Calyptoblastea is, " A sub-order of 

 Hydroida in which an external protective receptacle (hydrotheca or gonangium) invests 

 either the nutritive or generative buds." According to this, any hydroid having hydro- 

 thecae or gonangia belongs to this suborder, and as this species possesses developments of 

 perisarc, which are so much like hydrothecae that there is only an artificial, no natural, 

 distinction, it follows that we are dealing with a form that stands very close indeed to the 

 sub-order Calyptoblastea of Allman. 



1 From xolXutztus, covered, and spadLx, the hollow process in a sporosac about which the generative elements are developed. 



