Gray (1862) gives a somewhat lengthy generic description accompanied by a good figure 

 of the type species. His description is as follows: 



"The coral coriaceous, tubular, circular, and simple below, compressed, subquadrangular, 

 tortuous, and more or less branched above, the branches being similar in size and form to the 

 main stem. The main stem and branches furnished with more or less elongate, subsolid, slender 

 branches, which are placed on the edge of the large holes in the main stem and branches 

 which communicate with the main tube. These branchlets, (and sometimes the branches at the 

 base of them) are furnished wäth large cells for the polyps, which are placed in one (more 

 frequently in two) series on each side of the branchlets. The polyp cells are rather large, 

 circular, nearly superficial, and furnished with a cup divided into eight conical connivent lobes, 

 each lobe being formed of some transverse spicules at the base and some obliquely-placed 

 spicules diverging from each lateral edge toward the top above". 



Studer (1878) simply quotes the definition given above and, in 1887, gives a lengthy 

 description which is translated in the Challenger Report (1889). This may be condensed 

 as follows : 



Colony with a flattened stem bearing polyps on its margins and one face. Coenenchyma 

 of two layers, cortical and medullary. Cortex with spicules varying from spindles to club-shaped ; 

 thick and polypiferous on one side of the axis, thin and barren on the other. The medullary 

 portion has a very thin cortical layer and bears no polyps. Medullary mass consisting of closely 

 approximated rod-like spicules united by horny material. Stem and branches inroUed on the 

 side which does not bear polyps. It thus happens that in the stem and larger branches the 

 margins will often touch so as to form a hollow tube, while the smaller twigs only exhibit a 

 channeled stem. 



Germanos (1897) discusses this genus at considerable length and divides it, very strangely, 

 into two sub-genera on the basis of the presence or absence of a stem. The present writer 

 agrees with Hickson, and Thomson and .Simpson in regarding this division as unwarrented, 

 especially as he (Germanos) includes Solenocauloji tortiiosuni in his subgenus Malacosolenocaulon, 

 which is characterized as without a stem, when the figure given by Gray in connection 

 with his original description of that species shows an undoubted stem. Germanos added three 

 new species to the genus, i. e. Solenoca^ilon sterrokloiiium^ S. diplocalyx and 6". akalyx. 



Hickson (1903) made a somewhat extended study of numerous specimens of this genus 

 and concluded that Solenocaiilon torhiosiim Gray, 5. grayi Studer, vS". tuötilosa Genth, and Leit- 

 coella ccrvicornis (Gray) all belong to the same species, S. tortiiosuiii, and supports his thesis 

 by what seems a somewhat labored argument regarding the action of parasitic or symbiotic 

 crustaceans on the growth of these forms. He then adds a new species, S. ramosa, which seems 

 to be established on much the same sort of characters as are the species which he discards. 



Thomson and Simpson (1909) recognized two valid species, S. sterrokloiiitivi and 5. 

 tortuosum among the specimens collected by the "Investigator" in the Indian Ocean. These 

 writers also point out the inconsistency of Hickson in establishing his species S. raviosa "when 

 the only diagnostic feature seems to be the tunnel-like expansions". 



The present writer feels that there is little gained by substituting such terms as sub- 



