GENUS ENTOMACRODUS — SPRINGER 



Preopercular series of pores (fig. 2) : For tlie purposes of this study, 

 the first pore position is dorsalmost and occurs at about tlie level of the 

 greatest horizontal distance between the posterior margins of the pre- 

 opercle and opercle, excluding the branchiostegal membrane. The 

 pore positions in most specimens number six, describing an arc between 

 the first and last positions. The last pore position (ventral and ante- 

 riormost) is just ventral to the posterior corner where the membranous 

 margins of the lips meet. Dorsal to the first pore position are a group 

 of scattered pores. Some difficulty may be encountered in deciding 

 which is the first pore position. Examination of the illustrations of 

 the species should facilitate this decision. The pores at the various 

 positions may be simple (one pore), paired (two pores connected more 

 or less horizontally by a canal), or in multiples (more than two pores 

 o 



Figure 2. — Diagrammatic illustration of pores included in preopercular group (solid dots): 

 a, all pore positions simple; b, first, second, and sixth positions with simple pores, third 

 and fifth positions with paired pores, fourth position with multiple pores. 



connected to a common canal). A count of the number of these 

 three types of conditions at the pore positions is a useful taxonomic 

 character. 



Pores before anterior nostril: A count of the number of pore open- 

 ings closely adjacent and more or less anterior to the anterior nostril. 



Lateral line pores: Anteriorly the lateral line pores open into a con- 

 tinuous canal; posteriorly, on the midside, the pores occur in more or 

 less regular, separated pairs, the members of a pair joined by a short 

 canal. Large or small gaps in the occurrence of some pore pairs 

 should be ignored in determining the level of occurrence (usually below 



