HYDROCORALLlNE GENUS ERRINA, 877 



style in the Gasteropores ; (2) no style in the Dactylopoi^es ; and 

 (3) the Dactylopores, or some of the Dactylopores, guarded by a 

 grooved lip or spine — called by Moseley the " narit'orm process." 



To any one acquainted with Moseley's classical memoir of the 

 Stylasterina (8), and with the subsequent literature, which is not 

 very extensive, it might seem a simple matter to determine 

 whether the specimens about to be described belong to any one 

 of the three genera or not ; because, according to Mosele^^'s 

 descriptions, the following characters were diagnostic :- — 

 Errina, with only one kind of Dactylopore. 

 Lahiopora, with two kinds of Dactylopores. The larger kind 

 of dactylopore with a nariform process* and arranged in 

 rows. The smaller kind of dactylopore, without a nari- 

 form process, ai-ranged between the rows. 

 Spinvpora, also with two kinds of Dactylopores. The larger 

 kind of dact3-lopore with long grooved spines, not arranged 

 in rows. The smaller kind of dactylopore at the base of 

 the larger ones. 

 Moseley's memoir was published in 1881, and since that date 

 only four new species of Errina and one new species of Labiopora 

 (L. moseleyi) have been described ; but owing to the rarity 

 of these Hydrocorallines in the seas that have been recently 

 investigated, very little progress has been made in our knowledge 

 of them. 



The specimens from. New Zealand and elsewhere that I have 

 examined convinced me that a thorough revision of the genera 

 was necessary, and consequently the task of naming Professor 

 Benham's specimens has taken me much longer than I anticipated. 

 The general results of my investigations have been to show that 

 the limits or frontiers between the three genera are ill-defined 

 and that it is necessary to accept von Marenzeller's (6) proposal 

 to unite Lahiopora with Errina. 



In the first place, I have found, as von Marenzeller (6) has 

 done, that the presence of two kinds of dactylopores is not a very 

 reliable chai-acter ; because in some forms that are otherwise 

 closely related the dactylopores of the smaller kind that have no 

 grooved spines may be numerous, scarce, or altogether absent 

 (e. g., Erriout novce zelcmdice). A genus such as Lahiopora 

 cannot therefore be absolutely separated from Errina by the 

 character of the dimorphism of the dactylozooids. 



Moreover, the arrangement of the grooved spines in definite 

 rows is another character that is subject to considerable variations 

 and cannot be relied upon for diagnostic purposes. The arrange- 

 ment of these processes seems to be correlated in some way with 

 the method of grov/th of the hydrophytum as a whole, and that 

 is again, I believe, dependent upon the conditions of the en- 

 vironment. 



* The tenn "nariform process" introduced bj' Moseley is not very convenient, and 

 I have consequently used the the expression "grooved spine" for tlie cmnostoal 

 processes t!mt shelter the dactylozooids. 



