Table 2. Neuron density by cortex layer.

Brain Area	Cell Layer	Neurons
		I	II	IIIA	IIIB	V	VI	Area Mean
	Delphinus delphis (Brain: 783g)
APL		2,970	343,613	18,008	11,630	14,256	10,598	16,846
SLL		2,814	57,963	30,201	24,386	17,914	16,038	24,886
Layer Mean		2,892	50,788	24,105	18,008	16,085	13,318	20,866
	Tursiops truncatus (Brain:1,559g)
APL		4,690	35,224	13,765	10,630	12,922	11,463	14,782
SLL		1,876	43,144	21,728	17,508	15,632	14,325	19,036
Layer Mean		3,283	39,184	17,747	14,069	14,277	12,894	16,909
	Ziphius cavirostris (Brain: 2,004g)
APL		938	23,448	9,379	8,910	9,848	10,786	10,552
SLL		321	34,234	11,724	7,503	12,193	6,096	12,012
Layer Mean		630	28,841	10,552	8,207	11,021	8,441	11,282
	Orcinus orca (Brain: 6,215g)
APL		285	31,889	13,131	10,183	11,255	7,503	12,374
SLL		703	42,441	22,510	23,213	16,648	15,476	20,165
Layer Mean		494	37,165	17,821	16,698	13,952	11,490	16,270

Neuron cell packing density ranges for four species of odontocetes by cell layer and brain area. APL = anterior paralimbic lobule; SLL = supralimbic lobule. All values represent average neuron counts.