BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Zooecia having a chitinous frontal. Intertentacvtlar organ present. Larva a 

 Cyphonautes. No avieularia. No dietellae. Operculum with thickened border. 



Historical. The family Electrinidae was established in 1851 by D'Orbigny for 

 species possessing " celhiles en cornet," and was based on the genus Electro. Lamour- 



oux, 1816. Two genera, 

 Canfla and Cohered, which 

 D'Orbigny included in the 

 family at that time, had to 

 be withdrawn, because they 

 did not have the same larval 

 features. The Electra pilosa 

 group has been the subject 

 of numerous anatomical 

 studies. 



The. Membranacea group 

 is also a natural division, 

 and it is considered as con- 

 taining typical Membrani- 

 pora, which is the basis of 

 the family Membraniporidae 

 Smitt, 1866. The inter- 

 tentacular organ is known 

 here also. In 1906 Miss 

 Robertson discovered the 

 Cyphonautes larva in Mem- 

 branipora villosa, which 

 therefore belongs to the 

 same group. 



Electra and Membrani- 

 pora, having similar larval 

 forms, belong to the same 

 family, Electrinidae. This 



. l-opercular 

 | valve 



Jlareal spines 

 -^-gymnocyst 



--opeslum 



- flagellum 



FIG. 18. Genus Electra Lamouroux, 1816. 

 A-E. Electra pilosa Linnaeus, 1758. A. Several zooecia, X 46, 

 illustrating structure. (After Hincks, 1880.) B. Drawing show- 

 ing intertentacular organ (i. o.), X 20. C. Lateral wall, exhib- 

 iting multiporous septulae (s), X 47. D, E. Uniporous septulae 



of the distal wall, X 47. (B-E, after Levinsen, 1894.) name, given by D'Orbigny, 



has the right of priority. 



Classification. The known genera of the Electrinidae are as follows : 



Electra Lamouroux, 1816. 



Membranipoi'a Blainville, 1834. 



Heterooecium Hincks, 1892. 



Pyripora D'Orbigny, 1852. 



Herpetopora Lang, 1914. 



The two latter genera have been placed in the family on account of zooecial 

 resemblance, and not from a study of their anatomy. 



Genus ELECTRA Lamouroux, 1816. 



1816. Electra LAMOUROUX, Histoire cles Polypiers Cornlligenes flexibles, p. 121. 



The frontal is a gymnocyst. There is a circle of spines around the frontal area. 

 The distal septulae are uniporous. The lateral walls have 2 or Z multiporous 

 septulae. 



